It also means you raise the redline of the engine so you are increasing the power band and it makes the engine more reliable.
There is an article that covers this on the main site which I added a week or 2 ago:-
http://www.torquecars.com/tuning/engine-balancing.php
Don't look at the headline power gain - with other Modifications it means you can go silly power wise without worrying too much about blowing the thing up.