I haven't encountered any big debates regarding tweeters in vs out. Personal preference is all that matters.
It is more difficult to achieve the recommended time/distance alignment with the tweeters outboard, though I no longer concern myself with the time alignment of the bass/treble sections and simply place them by ear.
For my ears, I do find tweeters outboard preferable with both my .7s and the 1.7s I owned a couple years ago. I find tweeters inboard results in too narrow a sweetspot and despite Magnepan's claim, I find tweeters outboard provides the best imaging focus, if at a small detriment to soundstage depth. Tweeters inboard makes many vocalists sound as though they're standing many feet behind the rest of the ensemble. I don't find this to be the case with any other speakers I've owned, which leads me to doubt that's a trait faithful to the recording. Since when does a rock band's front man stand many feet behind the guitarists?
That's my take on it but again, all that matters is what you like. These speakers are so sensitive to placement changes that you can experiment to almost no end. I like to use a good vocal track like Ballad of the Runaway Horse to lock in the imaging and tone. Once I get Jennifer Warnes' voice sounding most life-like in size and presence, that's usually a good placement for everything else.
