Hey Eric,
The M1.0t is a very good match with the Martin Logans. I have the same ESL's that you mention, and I've driven them with a stock M1.0t, a stock M400t, a stock M500t, and a MKII modded M500t. For my ears, the modded M500t is the best choice. Over the next month or so, an M1.0t is getting shipped off for MKII opt 2 mods. When it gets back, the M500t MKII will get a rest, and I'll have a decision to make.