rear firing tweeters....

I had those Snells. E-IV, I believe? I liked them, but not necessarily because of the ambience tweeters. I think they were just good, high-value speakers.

To me, it seems a rear-firing tweeter is basically a reverb unit. There will be some delayed arrival at the ears, delayed enough to not cause phasing errors, but perceived more as an "echo". Ultimately, I'm not really comfortable with intentionally smearing the HF response in time to add "ambiance" beyond what is captured on the recording (or not).

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!

"If you want to hear just what's on the recording, no more no less, sit in the narrow sweet spot with nearfield monitors. If you want something that sounds like live music filling your listening area, go with omnis, bi-polars, or at least something with ambient drivers such as the rear-firing tweeter."

I think that's a bit much. There are plenty of full-range systems which can extract what's in the recording w/o requiring nearfield seating and which don't need "ambience" tweeters. This doesn't need to devolve into a religous argument.