I have the 1.9TDI and it is a little noisy. A colleague has a 2.0 Altea and tbh I think I should have gone for the 2.0 over my 1.9. It's much smoother, and has a much better mpg than mine.
I get an average 42mpg, but my colleague regullaly gets 50's. I think a lot of it is down to gear ratio's, if I sit on the motorway at 70 the revs are at just over 2000, sitting at 80 and there up to 2500. the 2.0 has a 6 speed box, so a motorway cruise at 80 and the revs are right down at 2000.
My two pennys worth.