I think it's really important that you spell out what you are looking for in a RIP. Is it nesting, tiling, layout, advanced Postscript rendering, custom ink limiting, etc? People are often very quick to jump to using a RIP because they think it will improve their quality without knowing much about it.
Illustrator actually has a built in RIP that's really good and can print to any printer with a driver. It's fast and does a great job. And today's driver offer incredible built in linearization that you can profile on top of. It's actually difficult to get as-good results from a RIP! And this is coming from someone who's been making a living, in part, by traveling around the country helping people setup RIPs for over 2 decades.
Printing to the 9100 from Ill *is* fast isn't it? And super high quality, especially when the color management is dialed in properly. Sounds like you've saved yourself from a big, expensive headache. Should you need further PS rendering and or nesting capabilities ImageNest or Overdrive Layout are two notable options to consider.