I had the EM 40s, the ESLs and now the Classic 9s. Honestly, the EM40s don't compare to the electrostatics and the classic 9s are a substantial improvement over the ESLs in two important ways. One is of course base response but the second and more important is the height of the panels. With the ESLs when you stand up you loose the highs and they just plain don't sound as good. I have not seen that with the Classic 9s. As far as space goes, they have a deeper cabinet but otherwise the difference in footprint is minimal. Here is a photo of my setup with REW measurements with the subs turned off.