Well - I seem to have resolved the problem.
I am in no way suggesting others do this - I am merely detailing "what worked for me"
1) Uninstall every piece of Line 6 software, using an uninstaller to "clean" anything left behind (I have a Guitar Port, a POD-XT, a POD-HD500X, a Variax, and the Helix, so there was quite the trail here)
2) Reboot
3) Using Zadig (Google it) I manually installed the latest version of the Windows libusb release (it's part of Line 6's driver base, and while I can't really tell how old the version is by inspecting the files that Line 6 uses, I can tell you that (per the docs from the devs) any version prior to the latest on the libusb github page had serious issues with numerous USB hub devices (and not hubs as is things that hang off your PC, hubs as in the chip devices on your motherboard)
- the OS saw my device immediately
4) Install Line 6 Updated v1.17 (as far as I could tell this is the release that added support for Helix)
- updater saw my device immediately
5) Manually performed an off-line install of HELIX_Floor_v3.01.0_0x5a8c6f191_bundle.hxf
- updated without issue
My Helix has survived several reboots without issue. Now I just need to get the editors and whatnot installed to support my older devices and pray none of it shoots the Helix in the face.
Again, try this at your own risk, but it worked for me after virtually nothing else did and Line 6 told me my only recourse was to pay someone to fix it.
Line 6 - I'd seriously suggest your QA / DevOps folks try a little harder at releasing robust software. If you forked libusb at some point it should be noted in the docs so people know what version it is you're using. And you should update your version. But what do I know.....
EDIT:
Well, I was actually able to dig into the Line 6 driver archive (release "Line 6 WinUsb Driver v1.0.0.3 Installer.exe") and inside that package I can see they ARE using the latest libusb release - so I'm extra puzzled. It may simply be that I had multiple drivers installed that were in conflict. While I'd like to believe that's not possible, it's certainly not out of the question with Windows. As to why my Mac didn't work I have no idea - all of the Line 6 software I put on that was latest-and-greatest - if the USB driver base was truly 1:1 with the current version from libusb it should have worked on the Mac no issue - but it did not.