With my new mac mini system, I got everything to work properly and ended up with a recording I'm very happy with. That's with a ton of vi instruments, Ivory, TruePiano, Kontakt, MSI...
Every recording run (rendering?) was not perfect! There were a few glitches here and there. But ultimately, after only about 3 runs, the recording was glitch-free. I'm just assuming the first several runs were dealing with memory concerns, but I don't know. (and the bounce-to-disk seems to be glitch-free as well)
Still, when you consider it's just a mac mini pulling all this off (oh, and DP5 too! Forgot about that) -- it's pretty amazing. I'm totally willing to put up with a few glitches now and then to be able to end up with a huge, 9-minute orchestral piece, totally in the digital realm.
I think it's just amazing.

Fred