I think that your concern about the condition or durability of most medium format equipment may be a bit unnecessary.
I've been using a Mamiya C330 and a few lenses for more than 30 years, and I think I have had to replace one errant screw. In addition, I had them CLA'd at about 25 years in, because it seemed a good idea.
My Mamiya 645 Supers and Pro have not needed any service since I bought them - although the Supers are now sold.
As you have a darkroom, I would suggest trying a lower cost option (a TLR or a 645 Super with a single lens). You should be able to tell fairly quickly whether you like using them. If not, you will likely be able to get most of your money back upon resale.
All your listed pros and cons are useful and relevant, but actually shooting a few rolls may very well tell you more.
+1, with the exception of I don't have a 645 camera.