I am using the 11x23 for crit racing. I found that the Ultegra cassette works very well with my drive train.
Cost effective though heavier than dura ace .My perfered seize not available in dura ace (12-30) if it was I would buy dura ace despite the cost save the weight inportant to me.
Shimano Ultegra 6700 is a great product and hope they keep making this line of cassettes for a while. If you keep it regularly clean you can get 4000 or more miles on it (depends on how hard you ride too).