center channel

I have an all martin logan speaker system, and want to experiment with a different center speaker. I currently use a Martin Logan Logo, but thinking of taking one of the Martin Logan SL 3 surround speakers and use it as a center speaker, and putting Accoustat or ELF speakers in surround. Use Martin Logan CLSiiz up front
I would recommend staying within the ML line and model, if possible, for the rear speakers. You will generally get a much smoother front-back transition by doing so. I know my (now) all-Gallo surround system benefited immensely when I replaced my infinity rear channel speakers with Gallos.

Good luck!

I used Magnepan center with my Electrostat Hybrids in the past with great results.
I'd recommend phantom in your case...
I think you need a center with those, I really needed one with my Estat's but they didnt have a curved panel. Even with a center that doesnt match it still sill be better the Phantom IMO.