Moving to a dynamic speaker from a Electrostatic

I had Innersound Eros and switched to Acoustic Zen Adagio. This was because the Innersounds were too "beamy" (very small sweet spot) for my taste.

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.)