I've never had the 32C only the base version, though I've never been asked to pay for an upgrade. Curious. I can certainly understand why you bailed, though. Pretty much all of their plug-ins seem to be "for Mixbus or Mixbus32C only", which seems like a significant restriction.

FWIW, I started with Mixbus as it was available on Linux, having been developed upon Ardour, which was originally a Linux DAW. Most software I get is first informed by "can I get/use it on Linux?". If the answer is no, then usually the software is dropped off of the short-list unless there's some compelling reason to keep it there ... BIAB, is an obvious example. A frustration with that is that, to use a Windows application that doesn't run on Linux, means changing from my "home" OS to use it. I spend 95% of my time in Linux, so that's a real nuisance and it adds to my periodic self-debates on "why am I still fighting BIAB's multifarious quirks?". I have only two software packages that I can't (presently, anyway) use on Linux, BIAB and my PCB-CAD. Most other Windows stuff will run in Wine' or if not there, in VirtualBox.

Jazz relative beginner, starting at a much older age than was helpful.
Kawai MP6, Korg M50, Ui24R, Saffire Pro 40.
AVL:MXE Linux; Windows 11; Win8.1: Scarletts
BIAB2022 UltraPAK, Reaper, a bunch of stuff.