Personally, I was never entirely happy with either RTG system on 3.x (I've used both for years). Whilst they worked, every system I ever used felt as if they only accelerated the most basic functions using the available hardware. On my CGX 4.2/Permedia 2 install, for example, it was obvious that scaled/transparent blits weren't remotely accelerated, despite the fact the hardware is perfectly capable of it.
Other than basic integration, what I'd always wanted to see was a retained mode graphics library (basically one where you'd queue up some rasterization commands, then have them issued inside a hardware lock using whatever acceleration exists) designed especially for RTG hardware. Instead all we ever really got was a few chunky pixel copy functions.
