My external bb (ultegra) on my everything bike had about 5000km on it before it was run over, its now on my dedicated commuter (80s steel mtb dropbar conversion) and still going strong, neither of these bikes had the bb shell faced and personally I dont think its important the cups will follow the threads regardless, prior to that I ran cartridge style shimano bb's I've had to replace 2 of these(all weather cyclist) but I cant tell you the kms. If given the choice I would always plumb for the external bearing type they are hell cheap,durable and easy to install.