I’m on Linux, and I’m still using Audacity 2.4.2 for production work due to its excellent stability and reliability. Of course it’s necessary to ensure that the AUP file and _data folder remain together (which is a non-issue for the self contained AUP3 format), but I’m used to that, so not a problem.
Note that Audacity 2.x cannot open AUP3 projects.