Daryl:
I sorta disagree, in that you have rightly described excessive head-space as being a 'pain in the posterior', not the belted case per se. Excessive head-space will accelerate head-separations in rimless, belted, and flanged cases, without discrimination.

Really, you are describing sloppy manufacturing tolerances in both chamber and cartridge dimensions, which is not a design fault of the belted case.

Personally, I reckon belted cases are great. The only rifle I currently own chambered for a belted case, the .416 Taylor, returns more than a dozen reloads with necked-up .338 Winchester brass until the primer-pockets begin to feel a little 'easy' and I toss 'em. Never had a head separation. Ever! You can't beat that!