[patdaly]

I'm not sure how you would hide the flange without feathering a bunch of bondo over it.

If it makes you more comfortable, it probably won't hurt, but you are going to have to but some places no matter what you do, so why not measure carefully, start patch panel slightly big and trim carefully until you have it?

The only real negative on a seamed joint other than the obvious difficulty in hiding it is you generally have an open side where moisture can get to.