I still seem to be experiencing audio dropouts and performance issues with the BBCSO. I also can't use anymore than 2 mic positions. I'm using Cubase on windows, 64 GB Ram, and a quad core i7 processor.
If you're on cubase, check that your daw isn't using VST3 instance of BBCSO (Reinstalled at each update of bbcso (not optimisation)), but the VST2 instance instead. For me it was the problem.