For all the careful thought you've given this and all of the pros/cons, that sale price you got is really the determining factor.
When it's *not* on sale, the base M2 Pro Mini is $1299. And if you want an extra 16GB of RAM (to match that of the base M2 Max Studio, it's an extra
$400.
The M2 is faster than the M1, and the M3 will be faster than the M2. Apple will always be gouging on memory and storage costs, but unless you need power *now*, the option to pay "half now" for an M2, and "half later" for an M3 or M4 option in a few years, is a great opportunity.
Thaaaaat being said, the first sale on the M2 Max Studio is going to undercut the optioned out M2 Pro Mini... which will make the decision a bit more difficult.