I had a Clifford concept 500 I think it was on my RS2k with the microwave and dual proximity sensors etc, and had no problems with it, just the odd false alarm due to cats etc in the proximity.
It actually saved the car once in Birmingham, was staying at the missus sisters house and some pikeys tried to get in thru the back window, they got the corner of the seal out and then it chirped twice and they legged it.
Saying that Chris off here who has it now has had a few probs with it going off all the time outside his house. Also I had to replace the brain on my mates concept 500 cos it died and left his car not working, and the siren never worked anyway.
I have a Toad AI606 on my RST and can't fault it, not given me a false alarm yet! Only thing I'd like to know is how to wire it in to the leccy windows, for some reason it wasn't wired up when fitted!
Lee