To close this off, I eventually found that, even with the improvements in 2.0.5, BRASS was just too unreliable. It also caused my sequencer (DP) to crash. I gave up on it, and the crashes stopped. Shame, because sometimes it could sound very good, but just too time consuming dealing with it's faults.
I'm sorry I didn't post this at the time - other fish to fry.
It just felt like it wasn't very efficiently programmed and everything else (including me) had to compensate...