My thumb button is my push-to-talk. It's not ideal sometimes, but I find it seems better than every other key I can easily reach with my left hand, and one that doesn't interfere with XVM or communication. My ideal PTT key for WoT would be a momentary foot-switch.
"After reading through this thread I've come to the conclusion
that more people cruise the internet looking for reasons why
X bike won't work in Y scenario rather than actually riding
their motorcycles." -- RyanR