As an EE you do know that electrolytic capacitors have a rated life of a certain number of hours at a certain maximum temperature with a certain maximum ripple and that the life is very much affected by the operating temperature and ripple.
I know these factors very well ! Just a few years ago AL Electrolytics were all 105degC. Now you can spec in 125 degC versions. I note on the ifixit board that all the caps next to the CPU look like tantalums and I am hoping are all 125degC guys. The Electrolytics on the top I would need to see the serial number. For longest life though you have my vote that something like 80% of rating is about as hard as you really want to run things. Anything over 100degC is a worry point and 110degC is a cliff no one wants to be near unless you totally know what you are doing.
I get why Apple chose this route, and it will probably work fine for the use and lifetime I expect. But I just don't like it . Will certainly be looking at the new pro whenever it finally appears.
As a last point, I always thought there would be a market for repackaging the guts of the mini in a 2X sized box with great heatsinks, low noise fans and 60degC max proc temp with < 34dBA performance at full load. It would of course void everything but could probably be done for ~$200!