deadlocked

You can have a wah/volume pedal if you attach an FBV3/Shortboard MKII/Express MKII board to the AmpliFi. If you only use the built-in pedal, then you can press hard toe-down to toggle between volume control/wah. If you have a board with an external expression pedal jack (FBV 3/SHortboard MKII), then you can attach an additional expression pedal and have one control volume and the other control the wah. You can also assign the expression pedal to one parameter within an effects block (according to the AmpliFi Remote Manual), but I have not tried it myself.
 
If you are considering getting a pedal controller for the AmpliFi, I would recommend the FBV3 or Shortboard MKII over the Express MKII, as they offer full control of the AmpliFi (you can bank up and down and turn individual effects on/off), while the Express MKII only allows you to switch tones ABCD within the bank, but you cannot bank up and down or turn individual effects on/off.

I have an FBV Shortboard MKII and I can bank up and down with ease. The extra buttons on the Shortboard will allow you to switch on the stomp, mod, delay, compressor and reverb, but not in the way you think: IIRC, the Function 1 button is tied to the comp, and the middle row of buttons are mapped sequentially (i.e. stomp to effect 1, even if it is not a stomp effect, modulation will be effect 2, delay will be effect 3 and reverb will always be reverb, this cannot be changed).
 
In short, bearing in mind the small quirk I noted above, an FBV Shortboard MKII will allow you to bank up and down, select any of the 4 patches within the bank and turn effects on/off. If you can return the FBV express and get the Shortboard instead, I would highly recommend it. If price is an issue, check out eBay and Guitar Center, you can usually find them used for much less (I just scored a one-month old FBV 3 from "flea-bay" at 40% less that way).
 
FBV3 will give you everything that the Shortboard will, along with nice colored rings around the effects so that you can see which one is the stomp, delay and mod. Also, being a much newer board, I would expect the FBV 3 to be supported much longer than the Shortboard. If Line 6 has not discontinued support for the Shortboard by now, I almost expect them to do so soon.
 
--- Edits below ---
I finally received my FBV 3 yesterday and I gave it a spin. It seems to support the same functionality on the AmpliFi, but I noticed the following differences when used with a Spider V:
 
- Color rings around the foot switches show the effect that is controlled by each: yellow for comp, orange for stomp, green for delay, blue for mod and red for reverb.
- The switches are mapped as follows:
   FS1 - Always comp (on both AmpliFi and Spider V)
   FS2 - Effect 1
   FS3 - Effect 2
   FS4 - Effect 3
   FS5 - Always reverb
  
Spider V 60 and up only: Function - One button looper (Rec -> Play -> Ovdub. Press and hold to erase).
 
Not sure why AmpliFi does not support color coded footswitches, since it works perfectly well with the Spider V series amp.
 
In short, if you have an AmpliFi, either the FBV 3 or the Shortboard MKII will work and offer the same functionality, but the shortboard, being older, will be cheaper. For Spider V, the FBV 3 offers more polish and, if the price is right, worth getting.

The FAQ below shows the specs (including size and weight) for all Spider V models:
 
Short answer, the 60 is just under 21 lbs and the 120 is under 30 lbs.
 
http://line6.com/support/page/kb/_/amplifiers/spider-v/spider-v-3060120240-faq-r834

I can confirm it is fixed on 1.02.2. I tried booting up with Variax already plugged in and also unplu/replug the Variax after the Helix had already booted up and in both cases, the models now change according to what was saved with the patch. Even if the patch was saved with modelling off and using mags only, the patch correctly switched to mags only when activated. If I manually change the Variax model and then press the same patych again, it will (correctly) reset the Variax model to the one saved with the patch.
 
I also tested the Tuning settings by using two patches, one that did not force tunnng and another one where I forced drop-D. In both cases, the Variax behaved normally. i.e. the patch switched to drop-D when forced, no matter where the tuning knob was at the time, and also the Variax stayed on whatever tuning I had selected on the knob if the patch was set to "Don't force".
 
I even tried to press the foot switches between both patches back and forth very fast and (just to see if I made it crash or got the models/tunings confused :) and I found out that it behaved as I expected (the Variax settings of the last patch I pressed were the ones that ultimately applied). Even the "Don't force" patch honored the status of the drop-D patch that I had selected before (i.e it stayed on Drop-D as I had it set not to change tunings).
 
Thank you DI and the rest of the team, for having the can of Raid on overdrive these past couple of weeks. I hope you guys have a restful weekend.