I have Mirus with RCG since Aug 2008, made more than 5000 trades, never once had a crash, and they answered my calls promptly. I am a happy customer so far, but I can't speak for others.
Took 6 months off from trading to study the markets and paper trade my new systems while I develop and test them, I use Zen-fire datafeed for my realtime test and paper trade and the feed has been rock solid, never a crash and they never give me any hard time for lack of trading activities for more than six months.