I get excellent mid-value separation by rating T-Max 100 at 64 or sometimes 80 and developing in PMK or PMK+. You will find one of my nudes here that was made on T-Max 100 120 roll film (EI 80) and developed in PMK+ (amidol added) for 7.5 minutes at 80 degrees. It demonstrates excellent tonal separation(posted 8162 days ago)