I had issues with double keystrokes at some point, but it was actually my typing technique what caused them. Anyway, you can adjust repeat rate using fn+F10/F11 IIRC.
LEDs work fine for me... unfortunately, they're too bright on the choc mini. I've had to "fix" them with black marker. The only problem I noticed was non-working numpad layer when connected through USB, but it's OK now.