Tweeters facing in or out ?

In my view, it's what the manufacturer says it should be--that's the person who designed the thing, he/she knows best.

You'll need to try it both ways and see what sounds best in your room. Generally, the sound from tweeters will be more prominent when they are on the inside (towards the center) vs outside.
Dave

Ive seen alot of reviews where the reviewer tries it the way the manufacturer intended but eventually swapped them and liked the results better.
Give them a shot each way. Going against the manufacturer's reccommendation might be more adequate with the accoustics of yer room.

Most are inside, I've done it both ways. Sometimes in a small room that dictates limited spread between speakers they may sound better on the outside. Try both and see what works best for you.

Dave

This is a no brainer.

It's your room and your ears. Keep solo vocals focused in the center. The speakers disappear. You'll find you can do this with either configuration. Then you have to decide if tweeters on the inside fit your taste for a more "intimate" soundstage. Most go for a wide and deep soundstage but your preferences in music genre are what matters most.

Speaker placement/room acoustics is at least 50% of this whole gig. IMHO