Looong request/post.
I saw the post about Usertracks below (and I support that) however my request is a bit different.
I think it would be a good idea to have a mechanism of crowdfunding specific Usertracks. Sort of local fiverr. For somebody who can play an instrument well and familiar with process of making UserTracks. Or even "classifieds" style posts. Meaning, musician would post something like:
"Can make custom User Tracks from $xx-$xxx depending on complexity. Specializing in didgeridoo. Here are samples:"
Initial supporters will get it for "shared" price and all others are by the price set by the artist.
Probably this can benefit both, musicians and PG. Specifically, larger audience / interest in BIAB. Another way would be for PG to trade Tracks with artist for discounted or free updates to the program, adding those tracks to main catalog or as optional Ultra-Super-Duper-Pack.
There are so many genres and instruments that have a very skinny presence in RT's such as Reggae,Ska,Punk,Disco,Tango,Oldies,Twist,Ethnic.. just to name a few. Some of these can be substituted with MIDI, but live is live

Sometimes unexpected surprises come. Pipeline posted a very nice Reggae rhythm guitar Usertrack (Thank you pipeline!) On that note, I looked at the tool Pipeline created: ReaTrak. Some advanced stuff! My head is spinning

I must admit, it is way to complex for me, but for someone who knows what they are doing, it seems like a very useful tool to bring UserTracks to life.