I'm almost done testing 214D, and I plan to post a report about it in the articles section when done. Just need to develop a roll of Delta 3200 that I shot this evening.
But T-Max 100 (TMX) gave interesting results: It shouldered off early. In another thread, Drew Wiley said this happens to TMX with several popular developers. So I mixed 214P, which is the same formula, but using .05 g of Phenidone instead of .08 g of Dimezone S. Here are the curves of both with TMX:
Phenidone (green curve) pushed the shoulder out a little, maybe 1/2 stop, and the shouldering isn't as severe. But what's odd is that Phenidone's shoulder is a sudden change of slope. In fact, the green curve is two straight lines. That makes me wonder if the shoulder is actually due to the low-speed emulsion taking longer to develop and thus giving a lower slope in the highlights. But only with some developers.
Also note that Phenidone gives a small apparent speed-increase (per ISO-definition), but at the cost of a softer toe.
Anyway, my advice is: If you shoot much TMX, use Phenidone and accurately shoot at box-speed. Else use Dimezone S.