John,
No particular thoughts especially if you're on the latest interim.
I can say this, just like on this forum, the few times I have tried to replicate a VST error someone was getting I never ran into the problems they had. As always each person's setup may differ just slightly enough.
As I said, I don't plan to use SoftSynths in MB3 (as of now) so I have absolutely no suggestions there.
I am off from the 24th through Jan 3 and so I hope to give all my 64bit plugs a thorough run in MB3 to see what falls out. Maybe by then 3.1 will be out (it's a bit overdue in my opinion, but as they say.... it's ready when it's ready).