Just how little jitter can MIDI deliver? At 31.25 kb/s, or 31 bits/mS, and 3 bytes (30 bits with start & stop bits)/shortest MIDI message, it seems you need at least 1 mS per event. Longer for more complex events. Can any sequencer reach 2 mS jitter?

In practical terms, I've played complex sequences on a 512K Mac without audible problems, but then I doubt I can discern 5 mS timing variances.