Personally I still like the 2 flavour option & the Pimax controllers the team is looking into making them extensible to support new tracking options as they become available.
But that's my personal Opinion. I can see though making the system button have a cap sense for swiping in 4 directions much like my old Samsung Omnia phone had with the optical sensor. (Otherwise horrible windows mobile 6.0 phone)
I ordered a set of both stick & pad. With Valve's new reference it doesn't take into consideration folks who may want the stick for the right hand & left having the pad. Where as it would be simple to have 4 skus
1) Pure Trackpad
2) Pure stick
3) Left Stick, Right Pad
4) Left Pad, Right stick
Final detail needed is to have game software companies pull controller pic to represent what you are using in VR. Ie shows Vive Wands, Oculus Touch, Pimax Controllers, valve knuckle etc. This would have been great for the Razer Hydra for example & more.
The pimax 4k for example shows a pimax hmd in the steamvr window instead of the vive headset icon in green.