This is mostly to see if there'll be any problems when merging these changes into Mixbus. I'm guessing there'll be some conflicts in these projects (and a lot more to follow...)
It'd be nice if we could use 'ARDOUR::config_dir_name' for this purpose (or perhaps 'PROGRAM_VERSION'). However, neither is implemented widely enough at present to make this practical. Keep an eye on them though, as possible future strategies.