Disclaimer: I own M3-Turbo S....
I bought these a couple of years ago and have them in regular rotation with Green Mountain Audio Continuum 1's, Maggie MMG/1.5 qr's, and Gallo 3.1's. Arguments regarding traditional boxes vs open baffles aside, I think these are one of the most well rounded speakers in my stable. They image very well, maybe being a little bit more forward than my Maggies and certainly more than my GMA's, the depth of the sound stage tends to be not as great as with others. However, these speakers look at dynamic hits and swings and handle whatever you can throw at them without breaking a sweat. The bass response is acceptable for most music, with the need for a sub only with electronic and pipe organ pieces. The off axis response from these speaks is simply amazing. Some would argue that that is is simply coloration from the open baffle design, but I suspect you like that particular "coloration" if you are looking at both of these brands.
As a point in fact, I have never heard another set of speaker that can do what these do at that price point. Simply amazing.
I have heard a large POP design at RMAF this past year, and while imaging and top to bottom balance was on point, I just didn't get the sense of visceral punch like I do with my Spatials. That said, Clayton Shaw is a great guy who will spend some time working with you around set up and any questions you might have. Also, he has a generous audition/trial period in which you can see if they work for you. Since I have owned these I occasionally stop into the local audio shop and listen to speakers that cost 3 to 10 times more and just smile knowing I have most of what those offer at a fraction of the price.
Let us know what you decide on (go with the Spatials)