Zipp 404 hub upgrade?

I know somebody selling a set of 404s (pre-CC). They have been used for both training and racing. I think I can get the wheels on the cheap but most likely will need to service the hubs or change them out. They are not damaged or anything, just ridden the piss out of them over the past 2-3 years. I would frankly prefer to have CK 45 hubs anyway and just use them purely for the rims/fairings. In addition to having them mainly as trainers and a backup set of race wheels.

Any pros/cons in rebuilding them for a set of non-race wheels?

Why not?

I think they are cartridge bearings, at least on the front, so should be pretty simple to service. Not worth changing out the front. For the rear, you just need to get the right spoke length with that hub. You might go a little beefier for the rear since it’s just for training or maybe wet weather or races on poor pavement.