It's $669USD compared to $79USD for that app only and converting is easier than trying to learn Biab.
PG should have a crossplatform format so it will install and work on both platforms.
As I said the only difference in the directory structure is Library > LibraryM
For $79 only it's worth trying first, it all worked for me I'm sure it will work for you.
If you are using AUD it's ridiculous the exchange rate at the moment to USD that's why I did an app only upgrade this year as the Audiophile was too much.
Can I use the same USB drive?I mean, when you point it out in that way, it's a huge amount of difference!
My plan would be to transfer all the data to a separate drive, format the existing BIAB USB Drive to APFS, then install the BIAB macOS version and transfer back all the data. I guess it would be better to do all of that first and THEN do the conversion as transferring that much audio data as uncompressed (ie non-mp3) data would take forever!
PS: oh and I did a search for that Library>Library M folder and could not find it.