My Apex? I got my P4 LEDs and reflector from PhotoFanatic in the mail and I almost immediately set about doing the upgrade. I cracked my light casing a little, though, due to a bonehead mistake.
It's not bad though. Just need to get a tiny dab of silicone to spread over it to seal it up.
The upgrade really was simple, though, as long as you don't mind voiding the warranty on a $60+ light.