I have a FWD A4, I went for the Fast Road Map with Chip N Spin, which is the middle map they offer in terms of performance, If your right foot is heavy (or TC is set to off) then the front wheels will spin, but if you are able to drive correctly then this is not a problem. Price was £250 inc before and after rolling road runs. The remap took approx 40 mins in total including RR runs. Most companies seem to be around the same in terms of BHP & torque improvements with regard to remaps, and the map I had was bang on the 45bhp increase that was quoted. Having only just had the map..just over a week, I couldnt comment on tyre wear, but again this would be down to your individual driving style and if you constantly floor it and spin the front wheels then what are you going to expect..as far as mpg is concerned I see a minor improvement so far, again only having had the map a week or so then this will possibly improve, though TBH I didnt have a fast road map for fuel economy reasons..if your looking to save fuel then they also do an economy map which offers improvements and reasonable power increases..depends on what you want...
Hope this info is of some use to you all..any further questions feel free..