I think, Spheres of Chaos works equally fast under AemulorPro as originally on a RiscPC. At least, I've never spotted any difference. Sluggishness could be caused by the method of screen redraw. If I recall correctly, on an Iyonix it is best to write to a buffer, rather than directly to screen, which is configurable in the view setup.
PMS really is a genereous offer.
I've kept a demo program for years on my hard disk, but the price to upgrade to the real thing always discouraged me, in spite of its fantastic capabilities (until now, I did simple music editing with ABC, which seems to be a sort of derivate).
This is really a very unexpected and very welcome present. Thank you very very much.