Originally Posted by hamster

What I hear from you is essentially "higher end groupsets will last longer because they are made better / with better materials".

While this may be the case at the level of 2300/Sora, I think it may be inaccurate or things may even wok the other way around at the top end. Remember that the name of the game in high-end road bike groupsets is "weight savings". No one chooses between Ultegra and DA based on the expectation that DA will last longer. People get DA because DA is lighter than Ultegra, and people get SRAM Red because Red is lighter than DA.

Take one specific example: cassettes. A 11-28 Ultegra 6700 cassette weighs 235 g. An identical Dura Ace 7900 cassette weighs 185 g. This 50 g difference allows Shimano to charge triple the price of a 6700 for a 7900 (here in the US, a 6700 currently goes for ~$60, a 7900 can be found for $180 if you look long and hard enough). What's the difference? For one, Ultegra is nickel/chrome-plated steel all over, and DA has several cogs made of titanium. Titanium is significantly weaker than steel, and it's inevitable that it will result in faster wear. Things are probably done the same way elsewhere: maximization of weight savings with or without some effort to keep durability in check.

If the objective is to minimize maintenance costs, an ideal choice may be something like 105, or, better yet, a mountain bike group like Deore (mountain groups are inherently tougher than road groups).