I've just found this post so thought I would sign up and write some blurb!
I ride a Specialized Carve Pro, nearly 2 years old and getting close to 10k miles. An unusual commuter to work but I ride the canal which is a pretty mixed surface, all weathers, all year so it gets a real hammering and so do I.
So far i've had to repair pedal bearings, replace 1 set of front and rear brake pads, 2 rear tyres and 1 front and its still going strong. I don't clean the bike that often so it spends its time very muddy and dusty but do regularly wipe the chain and spray WD40 on it.
Honestly, it's now probably due a service so debating on just buying a new bike to replace. The saving I make on not paying for travel in London make this option still very attractive!
I've had cheaper bikes over the years and I do believe paying a little extra certainly improves the longevity of components even when you don't take as much care of them as you should!