I have a client who has always used Plus-x 120 for her portraits. One day I asked why she didn't use tmax and she said it's because tmax "looks dead". I thought, OK, and one day she used a roll of tmax for the same subjects as she always shoots and processed in tmax 1:7 it did lack vibrancy, and looked 'dead' on the proof sheet. Now I can't put it into specifics like d-log H curves or finer grain or something more quantifiable, but with film, sometimes there's more than what we can quantify at work, although I'm sure one who knows could. I'm still a tmax/pyro kinda guy and don't use plus-x because it didn't work well w/PMK, although others might have luck combining it w/some other flavor of pyro or pyrocatechol. Richard is absolutely correct re:the combination of Microdol and tmax 100. Using an E.I. of 50 it is very fine grained and I had a client that used it exclusively for his professional 35mm portrait business. In 8x10 and 11x14 prints grain was not apparent at all. The combo didn't work w/rotary processing as there were very small surge marks that formed at the sprocket holes, so inversion had to be used for that combo. So if graininess is to be avoided, definitely use that combo.