Hollowtech bottom brackets are pretty bombproof in my experience. I use them on all but one of my bikes, and have only had to replace the BB on my 520. I think i got over 10,000 miles of all weather riding before replacing.
Even after 2 pretty brutal winters and 6 or 7000 miles on my winter/rain commuter, the hollowtech BB is still going strong.
I tend to replace square taper cranksets with hollowtech units because they require so little attention. I remove the crank and cups once a year as part of a maintnence schedule and to grease the threads and spindle, but even that probably doesn't need to be done to be honest.

You aren't missing a spacer behind the outboard bearing cup, are you? That would prevent the preload cap from being able to take all of the play out of the cranks when attaching the non-drive crankarm. The crankarm will instead bottom out on the splines of the spindle before it gets sufficient preload on the bearings.