Yeah, I was just looking at the center stack when I was trying out the new settings in iOS to avoid Maps navigating you places automatically. Luckily that bit is separate so you'd just have to swap the head unit and the surround for the vents/touch screen it seems.
I felt like the wiring and compatibility would be the primary concern. The physical swap seems doable with OE parts mostly. I figure the only way to really know is to get one and try it but I'd hate to be out whatever the head unit costs and shipping from Europe won't be cheap.
It'd be easier to just pull the stock unit and painted or have it wrapped but I really prefer the design of the euro unit. I'm guessing paint or some other spray on could get it close to the texture of the rest of the stack?
you would not need to buy the entire head unit and there are several components to it behind the dash (at least in Sync 3) - you
theoretically could get just the bezel and controls and ignore any additional electronics, which should be much cheaper
the next concern would be how comfortable with custom wiring? the controls you would be touching are merely buttons/dials, which should be the same number of pins just possibly hooked up using a different plug. If the plug is different, you could potentially make either your own in-between harness or just move the pins over to the new plug...it'd likely be doable
I wouldn't worry about Sync2/3 as you are only concerned with the actual controls here and not touching the Sync system itself