Any question answered...

I was giving serious consideration to switching to using a GXP-type bottom bracket, but was struggling to find the reducer cups I knew existed (a google-fail on my part). But I've found them now. On balance I think I'll try another set of BB30 bearings for the moment.

Reducer cups? They will just leave you with an inferior 24mm spindled crank and the same reliability problems inherent to BB30. Better off to either bang in a BSA adapter and use external 24mm cups or learn to live with BB30.

Tip - token ceramic / ti. bearings seemed fairly resilient, especially if packed with phil grease before installation. After a wet ride pull the cranks off and clean and dry the whole shebang to reduce the chance of it seizing due to water pooling in the BB.