So, I've got the TRP Hybird rear disc brake adjusted and bedded in.

It's way more powerful than the Bengal cable actuated brake. I can easily lock the rear wheel with the rear brake alone, and more importantly modulate short of that.

With the Bengal, the brake lever bottomed out well before locking the rear wheel.

I think had we had the TRP (and time to dial it in) we wouldn' t have melted the front rim.

Thus going forward, I think we'll be good with the rear disc, and the aluminum tracked Zipp on the front, particularly since we tend to descend fast without riding brakes.

as an abundance of caution, I'm thinking of going with a deep sectioned aluminum rimmed wheel ( DT Swiss) in place of of the Zipp front for mountainous rides.