Replaced the fuel pump on my 07 Denali at just about 200k. from talking to a few other fullsize GM owners though, it seems fuel pumps tend to die in these things between 100k and 200k. Not a bad preventative maintenance measure to get it replaced at the halfway mark really.
EDIT: also, I replaced it myself and it honestly was not as bad as I thought it would be. I've done break jobs that took longer. Took me about 2.5 hours altogether taking the tank out, cleaning it inside and out, replacing the pump, then reinstalling it.