Like most everything, there is always give and take. There are so many parameters to consider. So blanket statements rarely hold water. I very much enjoyed Magneplaners in years past and still do. But I enjoy a non-planer speaker more.
Do larger planar speakers produce more accurate sound?
Planar speakers generate sound pressure via vibrating membrane panels. The excursion of the membrane x radiating area= sound pressure. This would mean that for a given sound level, membranes have smaller excursion in larger planar speakers than in smaller ones. Does this mean that larger speakers will produce more accurate sound?
I am not talking about the obvious benefits of the larger speakers in terms of low frequency production, so let's not get into that.