Shimano Ultegra Bottom bracket replacement with Dura-Ace The bottom bracket on my Van Nicholas Astraeus is a creaking when going up hills. It's already been tightened recently, yet seems to creek more and more lately - probably due to the mileage (many, many thousands of miles).

The bottom bracket is a Shimano Ultegra 6700 (SM-BB6700), I've been looking at upgrading the unit.  I have an existing Shimano Ultegra crankset, would a Shimano Dura Ace 7900 Bottom Bracket be compatible with this setup?  I'm also looking at Hope bottom brackets, do ceramic bottom brackets last longer?  Or are they just smoother?
Providing that is of the same type and size it will interchange. As an example hollow-tech II 10 speed BB30 English will interchange Dura-Ace, Ultegra, 105 will all fit. Ceramic bearings are sold as smoother hence less resistance, will you notice the difference? It is hard to say, but probable not except in your wallet.