Most professional Mastering Houses wil NEVER normalise - it is considered as the biggest taboo in mastering.
It does indeed mess with the dynamics of the track.
There is a good few articles that can be found on this subject at
http://recording.org/modules.php?name=Forums.
Personally, I never normalise. I used to but I just make sure I get my recording levels correct or use compressors where you at least have control over the dynamics.