If you pulled the keys, and it still plays retail games, then I would say by all means flash the custom firmware, and test again. as long as you have the dummy.bin, you can always recover by buying a new board if it fails, and flashing the firmware to that. I personally have never liked the kami hack, as it is really easy to screw up. I would rather do an LTU2 install, even if it is with a phat liteon drive.
I got given a PC monitor few months ago but speakers are not very good. So I did a kamikaze hack the other week and decided to use my headphones on full volume so I cud here the beep noise when it unlocked. Jesus when I heard the beep I threw the drill piece across the room and nearly sh*t myself cos it was so loud. At least I didn't drill too far.