At the moment, I'm using both my A3 and A4 until the lease on the latter ends in a week or so.
One thing I've noticed is much more road noise in the A3. It's the only area I've found in which the A4 feels more sorted. Mind you, it's not that the A3 is bad or that the noise is particularly intrusive.
Just wondering if those moving from 8P A3s have noticed the same, or if it's down to the A4 being a larger car, or even the choice of tyres.