Originally Posted by
12strings
2. Going from mid to upper is mostly weight, with only Marginal performance gains, and likely comes with a DECREASE in durability. (Light, cheap, strong...pick two...)
Rarely is there a loss of durability. Dura-Ace might not be more durable than 105, but it's certainly not less. The materials improve (Ti/CF/Mg vs steel) so they can reduce weight without sacrificing durability. In many cases, there are minor changes than may improve longevity (bearing vs bushing, allen screws vs phillips).
From mid to upper tier the differences are very minor, but if you're thinking than Dura-Ace/Red/SR are in any way inferior to their cheaper cousins, you're wrong.