I'm a big fan of the MXO2 as well. Definitely check it out and compare it to the others. One of my favorite things about it is that it doesn't lock you into using it on one system. You can easily use it on multiple systems as well as a MacBook Pro. If you do a lot of H.264 encoding you should get the version with MAX for faster then realtime encoding. You can read more about it here...
http://www.matrox.com/video/en/products/mxo2/
I really have been happy with mine.
Greg