I have never driven a JIC coliover equipped car, but I know they are one of the popular coilover in Japan. I see a lot of cars with JIC coilover in Japan and people are happy with them. (that's where I came from BTW) So I believe they are decent.
oh my god! I just saw them, and I'm wanting to send my GC's back and go out for some of those! I know that SCC is putting JIC's on their project Silvia, so they must be good. I have also been to Japan and a lot of people run them on the street as well as the track over there. Very reputable, I'd definately do it.