Your Maggies are dipoles. Not better, not worse, per se, but certainly different than a pair of tweeters separated by 12" or so and firing in or out of phase.
One nice thing about dipoles is the null at 90 degrees, which can reduce sidewall effects. Everything is a tradeoff. I just don't necessarily buy the idea that a rear-firing tweeter solves enough problems to offset those it causes, but of course, we're talking about engineering here, which is as much a balance of compromise as anything else.
Nice speakers, those Maggie 3.6!