I'm just running the current version of XeO3 on the my C128 with the SuperCPU attached, and I still cant believe just how fast it is... The whole game (as it currently stands - scrolling, paths, animations, turrets) runs in around 20 scanline. Whats amazing is that XeO3 is designed to run in 2 frames so that its a nice slow paced scroller so thats basically 2 WHOLE FRAMES with nothing to do but fancy stuff!!! How cool is that!
With the turbo off, its taking about a frame - which is a lot. It just shows how much faster the Plus4 really is.
Im also really pleased with the downloader - Because it uses control lines and not timing code; it just works! AND I can switch the turbo on/off as it downloads without it doing something horrible!
The only current issue is that while everything runs, the background tiles aren't being drawn correctly - for some reason. That's a bit of a bugger...
Edit: I think part of the problem is that the C64 version has a multiplexor runing everyframe, and the sort is as well - when it doesn't have to be.