Rainbow's last game was Alive. Rainbow's staff if I remember was cut in half after the release of Reflex. (THQ was going under) THQ;s IPs was bought by Nordic who made everything after Alive and is making the new MX vs ATV game as well. I believe there are a few Rainbow hold outs on the team, but not many.
I agree that Reflex holds up well as a pick up and play game, although I'm in the minority, as I enjoyed Alive more - but that might've been because it's physics suited my play style more haha.