I am sure this was asked before but my search was not successful.
My Stevens Cyclocross bike came with a Ultegra 10 speed 12-27 cassette. It was time to replace it but was told Ultegra stopped making 12-27. The LBS offered a deal for a Dura Ace 12-27 and I took it.
I think I noticed a much smoother shifting experience and smoother rolling action.
I do not want to kid myselves because of the of higher cost of those DA for my Madone road bike. The smoothness would be worth it but the weight savings not.
Any help is appreciated.
Oh, BTW, I bike a lot long distance and relatively fast. Over 10,000 miles / year.