Have you heard of this new-fangled application called Adobe Photoshop/Lightroom/Camera Raw? It has some really far-out technology and a very difficult to comprehend workflow for both printing and proofing. It's absolutely revolutionised the complete photographic industry in the past 2-3 years.
But seriously, most people would be using Ps or Lr as they are the market leaders in RGB photographic/fine art printed output by a large margin.
When you mention that you only get good results if you first convert to CMYK, have you checked to see if the profiles your 9800 is using are RGB or CMYK profiles? Being a RIP, it is extremely likely the canned profiles are CMYK and this is why you would be seeing such a marked difference.
Regarding your last question, just about ALL of the popular Raw processing applications, such as: Lightroom, ACR+Ps, Bibble Pro, Capture One Pro 6, (maybe) DXO Optics Pro 7, etc. will be very easily able to accomplish your proofing request and show the proof on-screen with (in most cases) very accurately proofed colours/hues.