The question between the two programs is not what codec to deliver the final mov in but what codec do you need to edit the movie in. Express is very limited, it handles DV, HDV and Apple Intermediate and that is about it. So if you are getting DVCPro, ProRes and several other codecs it will not work without transcoding everything.
Also Express lacks Compressor, Motion, DVDSP and Soundtrack Pro. So you need to define what you need to be able to do in editing to determine which is better.
Express maybe fine if you are just cutting together DV or HDV footage.