Hi,
Perceptol is a very useful developer, as long as you rate your film to suit, and get acceptable sharpness to meet your own criteria. What I was saying is that I would not use it for film that is already exposed at box speed, and that I tend not to use it on faster films, as it can really hurt sharpness IME. (T-Max 400 might be an exception. I've never tried it, but I'll bet it would look nice.) For a low or medium speed film, I don't think you would be unhappy with the sharpness. In fact, it can take some of the edge off sometimes, which is part of the reason I like it.