afaik, warden is happy with keyclone. i have chatted with GMs, and spoken with tech support / employees of blizzard... and everyone seems happy with keyclone, no mentions of any issues. the main reason, of course, is the complete lack of bot capability.

as for key press lag in pvp... if your machine is adequate for the task, there will be no lag (ok.. might be something like 100 nanoseconds... but seriously)