The original ANT+ support used ANT+ burst mode and they have changed it to use a separate command channel at higher rates (16hz). We opted to support the newer approach as burst mode isn't a good solution for us (our ANT stack will need a fixup for it).
We don't use ANY proprietary code; our ANT/ANT+ stack is our own, our Wahoo support is our own.
As an open source project this is kind of the way it is for us, where TrainerRoad are 'lucky' in that they can use the SDKs from Wahoo and Dynastream without worrying about licenses and tainted code.
We DO support the USBXPress libs on Windows, but that was a platform issue with the old USB1 stick. We could deprecate it to be a little more 'purist' but sometimes you just have to eat the porridge.
I like to think that Richard Stallman would be proud of us ;)
Mark