113/263 critical hits just now using Oirandori (all during reduced enmity critical hit evasion.) This was using only AF3+2 body and 220 total DEX (on Abyssea mobs.) So +7~19% with 95% confidence. I'm guessing 10% although it could be 15% too. Maybe I'll go back and test using GH/SQ/RR. Should give a base critical hit rate of 85%. I don't really feel like going back through screenshots and checking on the proc rate, but it seemed to be somewhere about 1/8 or 1/16 (not great!) It can proc on WS, but it cannot proc and overwrite itself.