Just a warning to new Acon R930 users: always mount the trigger unit the right way on the camera hot shoe - ie with the trigger body sitting over the front of the camera.
Don't accidentally mount the R930 trigger unit backwards on the K-3 hotshoe (ie with the trigger body hanging over the camera viewfinder), like I did today.
The trigger 'catches' on the camera hot shoe VERY firmly when mounted that way, due to a spring-loaded pin in the trigger foot dropping into the empty pin hole in Pentax hot shoes. It took a lot of force and jiggling to eventually extract the trigger from the hotshoe (unscathed, luckily).
Many other flashes and triggers will do the same thing when mounted backwards on a hotshoe, of course, so it's not just an Acon issue.
Also can confirm that wireless radio P-TTL works fine on my K-3, as does HSS up to 1/8000 sec.