@lwrobertson, terrific post! The Tympani T-I’s were also my first planars, but mine were the original 1972 version, no A, B, C, or D. I also moved on to the Fulton Model J, but soon missed what a big planar does that NO box speaker I have heard can, regardless of size or price.
I later got into the original Quad (both single, and stacked pairs), and recently back into Tympani’s, with the T-IVa’s I now own. I once heard some big Sound Labs (driven by big Atma-Sphere amps) at a hi-fi show in SoCal, but something was seriously wrong---there was some what sounded like amp clipping going on. I have also heard the Sanders, which I thought were excellent. And now Roger Modjeski (Music Reference) is making an ESL, and offering it with a direct-drive tube amp. I’m planning on hearing it on my next trip down to California.
With the new Magnepan LRS being available for $650, there is no reason for an audiophilic music lover to resign him or herself to a box loudspeaker!