currently have an A4 avant (se 130) and an A2 (tdi 75) - and both have their distinct strengths, which do overlap in the middle somewhat.
comfort-wise, the A2 lags behind, mostly due to the ride quality - but also in cruising ability due to the smaller engine and lack of a 6th gear. There really is no way you can compare it favourably to a bigger saloon in that respect.
for zipping around town though, it's the far better car - although far less powerful, it's suited much better to start/stop driving and much more agile.
load carrying wise - only a roofbox will give you anything like the usable space available in a 'larger' car - the A4 got used for the first time last year for the annual Scottish holiday, and I think the A2 would've swallowed 2/3 of the gear, at best - I've also packed both cars for boot sales on occasion, so I'm pretty sure I haven't missed a secret magic compartment in the A2.
I'd be quite cautious before really recommending the A2 like it's a real load carrier to be honest - you can be creative with the seating arrangements, but if you have to seat more than 3 people, the scope for exactly what you can get in one, and how much of it, becomes limited. Suitcases are easy, but a bootful of the sort of stuff you need to take on a self-sufficient family holiday isn't going to happen.
It's far shorter and narrower than most 'family' cars - and there's only so much a clever engine/interior layout can make up for that.
I'd say it was a match for the next size class up though, definitely - a Focus/Astra sized hatch for instance.