You still have frames stators and diaphragms that resonate no free lunch for any loudspeaker. Also panels can rock back and forth as diaphragm moves. I do not feel these designs are as free from colorations as one thinks. Still estats planars ribbons can be wonderful sounding loudspeakers. Like all not perfect but for some maybe the best match for there room system or listening tastes. I spent many years with estats.
How many 'listen outside of the box' design?
Whether I owned electrostats or open baffle designs the majority of my audio life I've owned boxless speakers. My choices were made in part due to a logic of removing a 'box' from the equation of having to interact with a room. The more I thought about it it seemed a very logical choice. Why enter a speaker into a box and then have to deal with the resonation of the speaker interacting with the box and the room? I'm not saying successful box designs haven't been built, what I'm suggesting is box designs seem a more complicated way to achieve true room integration. I've discovered, dollar for dollar, I've exceeded most box designs. How many think as I do, or have experienced similar results based upon experimentation?