Originally Posted by Kimmo

No. Many of the things you pay more for contribute to durability. Forgings instead of castings or plastic or stamped plate, BBs instead of bushings, bronze sleeves instead of plain holes, stainless fasteners instead of chromed steel, electroplating instead of paint, etc.

I'm not sure about MTB stuff, but when it comes to road gear, Dura Ace has some mind-blowing little touches here and there; some of the engineering is quite extravagant. Some of the features are all about durability, but others are about trying out a new design to save weight; if it's a success the feature gets to trickle down. If not, it won't make it to the next version of Dura Ace. So DA can be a bit of a mixed bag; owners are beta testers to some extent (pros being the alpha testers).

Ultegra is pretty much the bomb, minus some of the fanciest touches, but also minus any questionable experiments - it's tried and true. (Stupidly short cable pull and hence unreliable indexing aside.)

I imagine it's a similar story with XTR versus the rest of the MTB range, but probably with some of the niftier unique features being more about function and durability rather than weight savings.

Top-level gear is best left for those who aren't paying for it, and/or those who consider such aerospace engineering to be wall art.

If you're really serious but not obsessed, second-tier gear is generally the smartest choice, if it won't break the bank. There's very little wrong with third-tier stuff too.

So yeah pricier can be more durable-but for most folks-not an issue-parts outlast their ownership

If you're really smart, you're happy with cheaper hubs, cranks and brakes, and you spend more on nicer shifters and derailers. And unless you can score a good deal it's hard to justify fancier chains and cassettes than 105/Deore.