@Wilse
Yep, I',m betatester for OS4 (on BPPC). Alas in the last few months I haven't had much in the way of time to myself to enjoy it :-(
From what I can see, your 030/25MHz should manage 28kHz playback (assuming you have no way of using >28kHz) for quite a few notes polyphony at least.
I hope there is a newer (read AHI) version in the works. A PPC native version for OS4/MOS would be cool - you could probably employ full interpolation then :-)
As for my original problem, I found the midi.library developer stuff (it looks nice and simple for what I need, which was the clincher, really). It sure is old, though. It needs updating with the current style proto headers and stuff which I am just having a look into. I should use CAMD really, but it is such a quirky one off that I can't be bothered :-D