I have had various electrostatic speakers since the late 1980s. I have owned Martin Logan SL3s since 1998. The SL3s are one of my favorite ML speakers. I have tried some newer MLs including the Accent but I did not feel they were as good. I have not heard the Quest Z, I have heard the request. The SL3s blend the panels with the bass much better than most.
Setup is very important with panel speakers. They need to be away from the walls to sound there best.
You don't mention the rest of your equipment such as the amp you are using. Martin Logan speakers really benefit from high quality electronics.