For what it's worth, I have 105 on my hybrid and Ultegra on my road bike. The 105 is ok, but I certainly notice that it is much "clunkier" than the smooth shifting Ultegra. Can't comment on the Dura Ace as I have been happy with Ultegra and never saw the need to fork over the xtra $$$ for DA. Good luck!

On another note, I took a peak at the Treks and Specialized roadies for sale at my LBSs the other day. Trek dealer has a gorgeous 4.7 Madone Compact (I prefer compact to triples) on sale. I was going to wait until next year to get a new bike but I am lusting after that bike. I really, really should wait but oh............. I am so tempted!