Yep, I've still got a throttle problem with mine too - I can't seem to remove my foot whenever I see open road ahead of me. Sadly, open road is rare in my neck of the woods.
In reply to the original post and having looked at the Audi website, then I guess it comes down to personal preference. I (personally) don't like the wheels and would have to change them back.
I don't necessarily think the price is outrageous in dealer terms as long as it is genuinely 400bhp. As far as I am aware, the only way you can get to that figure is via AMD stage 3. If they can't prove that, then I'd make like a banana. If they can, then you're talking about a £3300 extra on an already fairly loaded car.
The other consideration has to be your opinion of ex-demo cars. My (again strictly personal) opinion is that a demo S4 will have been given some stick. Of course, the majority of people buy S4s just for that purpose, so you could argue that any non-new car will have had a degree of punishment and that is what the car is designed for.
Of course, you could just negotiate a decent reduction off a new car, wait a while and have it fettled yourself.