I had illuminas for about a year and a half. I was satisfied with the ride and adjustability. I autocrossed on them for one summer (maybe ten events) and did lots of parkinglot tuning and hard driving, had no reliablility issues at all.
I have the koni yellows now, and the damping is noticably better, and the adjustability is better. Ive only had them on for about a month tho, so no word on reliablity, although there is a warranty on them.