I'd have to agree with that. A good quality Shimano square taper bb, or an Octalink bb, will usually last a LONG time. We haven't seen this kind of durability on many external cup bb's. Some are better than others, of course. Based on the ones I've worked with, I'd say Campy's external cups are awfully good in terms of durability, Shimano's are okay but not great, same with SRAM, and FSA's are inconsistent in that some wear out in just a few hundred miles while others do quite well. Subjective info just based on my own observations, don't take this to mean much.

Do keep in mind that a BB30 is not an external bb, the bearings are enclosed in the bb shell. We've not replaced many of the bearings, and have sold quite a lot of bikes with this system, but have had to grease between the cartridges and the shell a lot to keep them from creaking. We actually like the PressFit 30 system so far, with the nylon cups these seem to stay quiet (from what we've seen so far) and the bearings are sealed better by the nylon cups so it may help with durability. PressFit 30 uses the same, very large, bearing size as BB30.