Most people who have actually used different kinds of cameras extensively will have had more electronic ones suddenly fail than mechanical ones.
Mechanical ones may lose their adjustent slowly over decades (but then I have a 1968 Leicaflex SL, a 1969 Nikon F and a couple of other similar vintage cameras which are nearly spot on and probably never had a CLA).
Electronic cameras will more often suddenly die and require proprietary circuit boards to fix (which are also likely to be what's wrong with any "parts" cameras as well).
Re C.R.I.S. adapters: there are cheaper unbranded ones available and one can make one's own as well.
Just a few points:
1) The alternatives to mercury batteries are easy to use, accurate, dependable and can also be cheap.
2) Electrronic cameras are not inherently better than mechanical ones and mechanical shutters definitely *can* accurately expose slides.
3) For manually focusing a lens, AF focusing screens are almost always *not* better than screens desgined for manual focusing. They may be brighter, but don't snap into focus the same way. Especially with faster lenses.
4) Newer cameras are not always better than old ones.
Sorry for the rant....