As said by others, BIAB is just one of many music/audio apps I use daily which is not yet compatible with Big Sur. Running a dual boot with Catalina from an external drive is a decent work-around IMHO (or in my case, the other way around, running Catalina as default and Big Sur booted from an external drive). It's not the first time, and will certainly not be the last Mac OS update which require some patience ...

A beta version of BIAB for Big Sur currently being tested by PGMusic is good news! I guess it has been some hard work, judging from what I've heard from other companies, thanks!

Btw, iReal is a nice app as well. I use it frequently when I'm on the fly. But it doesn't fulfil all my needs, which BIAB does. Running it natively on OSX is more convenient for me than running the Windows version using Parallels. I'm confident that PGMusic will continue to support us MAC users as well.

Just my few cents ...