pfj1

How can they separate this from the effects of losing weight?

Unfortunately most dynohubs are essentially un-servicable. The ones that do claim some level of servicability (eg, SP) mention a very tricky re-alignment process when replacing the bearings that can only be done successfully at the factory. I've gone for an Alfine on my new commuter - it's been fine for the past year, will see how it goes.

Depends which one you buy! I bought a SON about 10 years ago, have done around 20k miles in all weathers, and have had zero issues at all with it.

Those "evolved" FPGAs weren't much of a mystery. They just used undefined parameters (inductive coupling, power supply rail glitching, etc) to achieved the trained outputs. They didn't work when the ambient temperature changed, or when moved to another example of the same FPGA.