I purchased a Cannondale a couple of years back as a donor bike. It had the RSX group. I was building a bike for a friend, he wanted upright bars so I bought some indexed twist shifters, I saved the brifters for future use and sold the frame.

I liked RSX, while I didn't ride it much I was impressed with how well it shifted. My friend has been happy with the bike, although he wouldn't know RSX from 105, Sora, Tiagra or Ultegra.