I'm trading my 2010 E90 for a new 2011 E90 in 6 weeks time and i am probably going to have the new car remapped - an extra 20 hp or so should be noticeable and more importantly the removal of the top speed limiter will be nice as i live in Germany and can use it on the autobahn.
The thread below has a few reviews from people who have the 'evolve' tune on their car and the general concensus is that a genuine difference can be felt from 4K RPM to redline and most people like the tune.
This is worth £600 to me. Let us know what you decide!
http://www.m3post.com/forums/showthr...=1#post9881440