Derailleurs

[Smokin Joe]

You've obviously never had a bike fitted with Simplex Prestige ..............................

Yes I have, and what's more I raced on it.

 

[Sittingduck]

Not sure if this has already been mentioned but if you want 10speed shifters you need to go for 105 or above.

 

[2Loose]

Hmm, maybe not quite clear, sorry; I was referring to a comparison of the full groupset. The Ultegra shifting on the back is noticeably, well, snickier; there's a more crisp feel to it. It also shifts better under load.
...

In summary, I genuinely believe there is improvement in experience as you move 'up range' but the return on the incremental investment becomes smaller as you go...

'Snickier' - I understand

I chose Tiagra because it was the top of the current Shimano 9spd groups, as I understand that the 10spd chains won't hold up as well for all year round commuting. I guess you pays your money...

 

[martint235]

I've not been able to fault 105 stuff and have started replacing most the stuff on my bike with it as the originals fail. It's rugged enough for commuting use and works efficiently. I'm put off by the cost of Dura Ace stuff, i think it's best left to dedicated racers.