"This is a very old format, and is also proprietary to Windows."
I was thinking that very same thing the last few days, WHY ?
No other software companies use wma that I know of, I think PG is the only one on the planet.
The Audiophile version needs to be lossless WavePack allowing for 24bit 48khz quality.
I think originally Biab was made as a fun thing for hobbyists, but it seems to be hard to get it to a professional audio software state for professional studio users. There seems to be no goal, dedication or enthusiasm to get it there, they seem to have to be pushed to go there reluctantly.
It seems to brush off on the staff also, no enthusiasm for change and making things better, new ideas, if things are done it's reluctantly to stop users complaining.
If the programming language you are using makes it too hard to add things easily and have to spend 6 months on the Mac version doing the same thing rather than a crossplatform language, crossplatform audio codec, Win/Mac released at the same time with same features, so it might be good to start looking at alternatives.
So that's my "Let's discuss the RealTrack audio format".