Situation with trackpad and joystic is an exception, and other exceptions are unlikely. There is not a lot of sence in building bulky architecture to deal with one exception. Moreover, it isn’t possible to keep cross-controllers unification in a level of SteamVR actions/binding anyway (and let’s not forget that, for the point of view of UE4, it also should be unified with another VR systems). Developers will need to deal with unification manually. One check more, one less - doesn’t matter.
Just another example: grabbing gun. Player with Vive controllers (old “wands”) can’t hold Grip button for a long time. I. e. natural setup is using one click (press-release) to take gun and then another click to throw. With Index, it makes sence to use grip press for grabbing and grip release for throwing. So we need one input event for Vive controllers and two separate events for Index.
PS Didn’t receive invite to discord with Knuckles btw. And a key for test content package either.