Digital_Igloo

Download it here:
Mac OS X: http://line6.com/software/readeula.html?rid=7880 Windows 7/8/10: http://line6.com/software/readeula.html?rid=7879

Logic and MainStage can map MIDI CCs to all sorts of functions via the Key Command menu, but there are almost 10,000 commands (!!!), so any attempt to map Helix's 10 stomp switches to a comprehensive set (beyond the requisite MCC commands, for which there is a template—8 TEMPLATES > DAW Remote) would be futile.
 
That said, we have plans to add more robust DAW control complete with DAW-specific templates sometime next year.

There's a template: 8 TEMPLATES > 02A 4-Cable Method (or 02B 7-Cable Method for two amps). Pressing FS2 (or FS3 and FS3 on 02B) will instantly swap your real preamp for one of Helix's preamp models.

Change the Variax Settings parameter to "Per Preset" and your parameters should come back. Out of curiosity, what FW did you update from?

From the hardware, it takes three seconds:
While touch-holding the Snapshot you want to copy, briefly touch and release the destination Snapshot. Press Knob 6 (OK).

There are lots of ways to do it, but the easiest method is probably this:
Build your "left" sound on Path 1. Set its Output > Multi block's Pan parameter to Left 100. Build your "right" sound on Path 2. Set its Output > Multi block's Pan parameter to Right 100.
If you want to build everything on the same path, you can:
Select one of your two Amp blocks, press ACTION, and use the joystick to move it down. This creates Split and Merge blocks. If necessary, move your Amp, Split, and Merge blocks accordingly. The Split should be to the left of the first Amp and the Merge should be to the right of both Amps. Select the Merge block and set its A Pan parameter to Left 100 and its B Pan parameter to Right 100.
Note that all paths are fully stereo, so if you have, say, a Ping Pong delay before the split and want it to bounce back and forth between Paths 1A and 1B, it won't sound stereo because both the left and right sides are being sent to both paths equally before being merged to mono at the Amp block. You can still accomplish this, but you have to select the Split > Y block and set Balance A to Left 100 and Balance B to Right 100.

Helix doesn't have direct matrix-type routing outside of home screen path Input and Output blocks except for USB In 1/2 Destination.
 
1) Doable, and it won't take up any of your paths. Assuming your main samples, synths, and looping is sent from Ableton via USB 1/2, set Global Settings > Ins/Outs > USB In 1/2 Destination to "XLR."
2) Obviously doable and it'll take at least one of your four paths. Set the path's output block to 1/4" instead of Multi.
3) You mean sends? This is also doable but it'll eat up two more paths. USB In 3/4 to Send 1/2 and USB In 5/6 to Send 3/4.
4) You've now eaten up all of your six analog outputs (XLR, 1/4", and Sends 1-4). You could cheat and use your fourth path to route from USB 7/8 to Digital, set Global Settings > Ins/Outs > Phones Monitor to "Digital," and use a stereo DI to convert Helix's Phones out to two FOH feeds...
5) By two sends you mean two USB channels from Helix to Ableton? There are no more paths to route Returns to USB outputs. You could always place Return blocks onto existing paths, but the path's output is gonna send the outboard mixer feed as well.
 
And again, this is assuming you only have one path/DSP for your guitar. The second DSP is wasted, as its paths are required for routing. Helix can accommodate track routing and monitor mixes for the MD and drummer all day. As soon as you try to feed separate mixes to the whole band, you're really looking at a dedicated monitor mixer or distribution system.
 
Hope this helps.

There's nothing precluding us from adding model select to Pedal Edit mode. Vote that sucka up!

We're reverting the pitch algorithm to the pre-2.0 version for 2.01. At least until we can get to the bottom of what people are hearing. Ask and ye shall receive. Thanks, everyone.  :)

Amp models have not changed. However:
Model defaults have likely changed Amp-model centric presets (beginning of FACTORY 1 setlist) have likely changed The impedance circuit on the Guitar In now defaults to "Auto" Resetting Global Settings (required for the update) may have changed some parameters that affect level

Works here. From the 2.0 hardware, press the PRESETS knob and then Knob 1 (Rename Setlist). From the 2.0 editor, click and hold on the current setlist's name.

Whatever you connect Helix to should typically have mixing capability, but here's how to do it anyway:
 
Add a Volume/Pan > Gain block. Move it down to Path 1B (or 2B if you're already using both paths). Move the Merge block down to create a duplicate output. Move the Split block all the way right to just before the Output block. Set Output 1A to 1/4" and Output 1B to XLR. Set the XLR Output block's Level parameter to the desired level.

You can do this today. :) Set Global Settings > Footswitches > Preset Footswitch Mode to "Lower Row." Switches from Stomp mode will appear at FS2-5 in Preset mode.
 
If you need to move stomp switches around, you can quickly swap locations by touching the two switches you want to swap for two seconds and then press Knob 6 (OK).

Press MENU and then Knob 6 (Global Settings). Use the joystick to select the Footswitches submenu and turn Knob 2 (Preset Mode Switches) to "Lower Row." Four Stomps appear on the top row and four presets appear on the bottom row (like HD500X's default state) To view 8 stomps, just press MODE to select Stomp footswitch mode.
 
Global Settings are not accessible from the editor software.

Bug. Will be fixed in the next rev.

The DSP allocation filter (the thing that grays out items in the model list) is different for each Path/DSP. They don't talk to each other; that is, DSP 2's allocation filter can't tell DSP 1 "Hey, you won't fit over here!"
 
At one point Helix had two completely different home screens—one for each DSP. It was done that way specifically to dissuade people from moving a block from one path to the other. In the end we decided "Nah, let's just explain it if people ask."
 
It's something we could add with some effort. It's on our list, but way down because copy/paste (coming soon for the editor) is such an easy workaround.

It's definitely a bug. We'll have it fixed in the next rev.

Our OWN expression pedal is the Line 6 EX-1. It's obviously fully supported.

Yep. Right when Helix started shipping, there was a perfect storm of OS X El Capitan and Windows 10 releases, both of which have been... let's say, brow-furrowing. Had anyone in this industry known what was going to happen, dedicated driver development resources would've been desperately dispatched many months earlier by many different companies.
 
And it's not just USB audio; the actual USB port drivers—that is, drivers that make the physical USB ports work at all on specific mid-2012 MacBook Pros and iMacs—are also, shall we say, folicle-liberating. We're talking the inability to boot many USB flash drives.
 
So pleading with a Line 6 product manager to hear your woes is like pleading with a flight attendant about a shared plane crash. We can empathize with your pain and wring our hands along with you, but in the end, we still have zero control over birds flying into the engines.

It's not about the switches as much as whether the UI MCU can interpret double-taps. The answer is yes.

Each Send and Return is mono. In the model list, you can select:
Send: 1, 2, 3, 4, 1/2 [stereo], or 3/4 [stereo] Return: 1, 2, 3, 4, 1/2 [stereo], or 3/4 [stereo] FX Loop: 1, 2, 3, 4, 1/2 [stereo], or 3/4 [stereo]

Press and hold the Delay's Feedback knob. Helix jumps to the Controller Assign page for that parameter.
Press Knob 6 (Learn Controller) and then the footswitch you want it assigned to. If desired, tweak the min and max values.
Press HOME to exit.

Ah, yes. Helix is doing both. It's sending your Instant Command, and then sending the preset's PC message immediately after. It appears as if your Instant Command was not sent, even though it was.
 
Go to Global Settings > MIDI/Tempo and turn "PC Send/Receive" off (which doesn't affect manual Command Center assignments). It should work after that.

There are a few ways to do it:
Assign the Level parameter of each Output block to a footswitch, set the max for both to 0.0dB, and swap the min/max for one of them. In that case, stepping on the footswitch will toggle the Output level on and off Add a Gain block to the end of each path, press BYPASS to disable one of them, and assign both to the same footswitch Start with 8 TEMPLATES > 02C TwoTones A-B

Unless your aux instrument or vocals require a lot of blocks, you can share Path 2's DSP:
On Path 2, create true parallel paths (start with a parallel path and then move both the Split and Merge blocks down). Set Path 1's Output to Path 2A. Set Path 2A's Input to None. Use Path 2B for your aux or mic. In the above scenario, you're using Path 1's whole DSP and half of Path 2's DSP for guitar, and the remaining half of Path 2's DSP for aux/vocals.
 
Obviously, if one's using Helix as a guitar processor only, they have to work pretty hard to run out of juice.