What do you use yours for? I love my FC660C but I really wish I could store all my Karabiner mods on it. Like double shift for caps lock, or caps lock as escape when pressed alone but control as a modifier.
The controller comes with the TMK firmware, but the real way to use it is to put the fork of TMK, QMK [0], on it.
You can do pretty much anything you can think of. Tap for escape and hold for Ctrl on Caps Lock is in fact something I got on mine. I also coded it for function keys on double tap for the number row, F13 on tap and F14 on double tap on the left corner key (Left Ctrl or Caps Lock depending on your preference) etc.
And that's really basic, people put whole macros in there.
