I don't see any difference in the quality between Sora, Tiagra, and 105 shifters. Ultegras do the same job, but are smoooth.
As for front derailure, I prefer the Tiagra or 105. I'm not that sensitive about weight, and can't tell the difference in performance on front derailures that are supposed to be "better". They weigh less, but, I have more extra weight around each ankle/kankle...
I do see a difference in the rear derailures. I prefer 105 or better. Tiagra is comparable, but...they just seem to need more adjustment. Make sure that you get a medium or long rear deralure cage if you ride with a triple. The short cages don't cut it.
I must admit that the best-working group I ever had was a long while back, before Brifters. Nothing shifted as fast and silent as a bike that I had in the 80s with campy (six speed on the rear). Super nice. I got the set from a bike shop that went out of business for like $40 (before the internet).
Last edited by Pinyon; 07-12-10 at 07:13 PM.