I had a BB, it was s/h when I got it and did 2 shitty winters and a shitty summer. Never gresed it and it eventualy dies when trying to swap it between bikes and the race had siezed to the axle so the bearing came appart.
I'd have one again, I'd argue it's certainly no more expensive in the long run than XTR even with XTR on sale at Rose, I'm not expecting more than about 1500-2000 miles from each one, so as the King did double that with me, and probably douible again without a service, that's pretty good going.
And they're anodised and look pretty.
Headset's are probably better value, IME I never get more than a year out of the default Orbit or S3 (mid priced FSA and CC headsets are one of the cases where they really do all come from one factory, TH Industries). And they're far harder to swap than a BB (although you can just buy the same again and swap the seals and bearings,leaving in the cups). So if it lasted 10 I'd be happy. The downside is I've never kept a frame 10 years except the road bike!