Moving to a dynamic speaker from a Electrostatic

Tough moving from Sound Lab to conventional speaker since they do things so differently.

I went from Sound Lab U1 to Dali Megaline because the Megaline is a fast cone system with dipole ribbon tweeter.

That made the transition much easier and Dali image is huge, much like the U1. The only negatives, Dali require four channels of amplification are fairly expensive, even used.

Since your Sound Lab M2 is slightly smaller than my transition from the U1, the Magneplanar 20.1 or even a smaller model might be perfect.

Maggies are quick, low distortion and good bandwidth and if set up correctly image very nice. Then there is cost. Magneplanar are the biggest bargain in high end speakers, in my opinion.

I've had good luck with both ESL's and dynamic driver's. Ultimately, your personal taste is going to be the deciding factor, but one speaker I recommend you consider is Vandersteen. I find them to be as coherent as any speaker I've ever heard regardless of design. Not only that, you should also look forward to what a dynamic speaker can do that ESL's usually can't. It's very likely you will find that you are upgrading the sound of your system in certain areas.

That said, the most important thing to keep in mind, I feel, is to consider what the entire system will be, and not just speaker A vs Speaker B. All the other components are every bit as important as the speakers. (I'm sure you already know this but I still think its worth mentioning.)

Moved from Maggie, Auditioned Quad ES. That was the sound I wanted but with better dynamics/slam, and at a lower price point. Ended up with OHM Walsh.

You didn't mention price point. But I just moved from the Dynaudio C1 sig to the Raidho D1. The Raidho to me sounds more like an electrostatic speaker but with better dynamics. I never heard the 'C' series but read they are pretty close for a lot less money (especially since the diamond series was released).
Good Luck ;)

I had ESLs for nearly 8 years. Started with ML Odyssey, but found the sweet spot way too narrow. Moved to a pair of Quad 2905s with a pair of REL subs and was convinced I could never go back to a conventional box speaker with cones. The Rockport Aviors I have had for over a year are superior to the Quads in every conceivable parameter. Of course a lot depends on the room and the associated gear.
NJoy