Hi Rob,
I'm currently running an hybrid on a M10000, no experience with SP8000.
I can get audio and video with reasonably good performances.
To get video I "hacked" Pluto setup and replaced xfree and video drivers with unichrome ones. They are the only ones that really work with xfree.
There is also a different project (openchrome, a fork of unichrome) that offers probably better drivers (their driver uses hw acceleration for mpeg2 and mpeg4), but they are for Xorg.
One interesting thing would be to try to switch from xfree to xorg and see what happens to the whole pluto setup.
I didn' try yet because I was focused to get a stable Pluto environment as close as plossible to the "standard", but now I could give it a try.
Nevertheless I wouldn't mind to have an opinion from Pluto guys regarding this. They certainly know better than me what kind of impact may have this kind of tweak (replacing xfree with xorg).
If they already know that doing this would break everything, there would be no point to test it ...
Regards
Marco