So far, everything in Open MPT is working perfectly within Crossover games. The only exception, is the VU meters in individual tracks. You can enable them, but they won't show up at all.
However, as they aren't even enabled by default, and most don't ever activate them, I am quite happy in listing this as 'Gold'
It performs it function flawlessly, there is very little difference between running this under Windows or Linux+Wine