Interesting about the 2009+ models....and annoying. I really liked the ability to flash the ECU via the ODBII port. Now I'm wondering about my late model 2009 GTI...I'll probably get a tune and whatever done to it at some point. I suppose I could use the excuse to drive to BC to have it tuned in person.
As for the clutch....I'm on my 2nd, going to my 3rd clutch in the TDI soon.
I don't drive super crazy, but I do give it regular "Italian tune-ups" now. Since I've started doing that my air intake manifold has been nice and clean...more or less, and the turbo never has a problem.
I've experienced a fairly gummed up air intake manifold and turbo in the past...and that's with aggressive driving, but extremely few WOTs. This contributed to my original turbo going bad.
I assume that the really cold weather that we get here from time to time also contributes to early clutch failure. They are more prone to slipping when it's -30 or colder...and slipping means more wear and less life.
The DMF clutches on the MK4's weren't that great. Getting a tune pretty much guaranteed that the clutch would need to be upgraded/replaced. I'm not sure about the clutches in newer models. But after tuning and the clutch going bad I would still think it's best to get an upgraded clutch that can hold more torque.