IMHO, I believe if you are the only one watching the movie, and you are sitting in the exact center you don't need the center speaker. On reasonable quality speakers, the imaging on the speaker should put dialog in the center where it belongs. Actually, that may be a better setting since you may not have to deal with timbre matching. However, if others are watching (or you are slightly off center), you do need the center since the dialog will not appear to come from the center.
Magnepan center...is it really needed ?
I have a pair of Magnepan 1.6 and the Magnepan center speaker and to be honest I don't ear much difference with or without the center channel ... Is it really necessary to have a center channel with the magnepan speaker or a 4.1 will be as good as a 5.1 setting ? Cheer Alex