If he wants to fit and forget,then the mavic and shimano options listed above might be worth a look.
Hahahahahahahahahaha! Good one! Mavic; known for their easy serviceability, supreme reliability and availability of spares.
We had a Ksyrium ES in our workshop for 7 months awaiting a spoke. Not multiples, not a rebuilt. A spoke.
Then there’s the R-SYS debacle, with the serious injuries, the recalls and the customers being given Aksiums to tide them over whilst they make a less dangerous product.
If the OP’s worried, build 2 sets, perhaps one set on 50mm tub rims and one set on Alphas (or Open Pros), you’ve then got 2 sets if something goes wrong. Hubs are sufficiently cheap that if something breaks just order a whole new hub and swap the appropriate parts, don’t fanny around waiting for spare freehub bodies.
Guesses on the cost of a Dura Ace freehub body?