5. Tie.3. The stain masks the grain of the film.
5. Both forms of pyro tan the emulsion providing more protection from scratches.
6. Separation in the highlights is superb when compared to MQ or PQ developers
7. It is probably the cheapest developer around when diluted to working dilutions.
8. if mixed in polyethylene glycol, which it should be, it lasts for an extreme length of time. I have never had any go bad.
9. the scale of the negative is enhanced because the film curves don't have unusual fluctations.
10. since the concentrates are liquids, it is quick to get ready for use.
6. Similar. Virtually a tie; it just depends on your preferences.
7. I'd have to crunch the numbers, but most pyrogallol developers like PMK are very inexpensive to use.
8. PMK lasts for years mixed in distilled water. It does not require propylene glycol when mixed.
I don't mean to badmouth pyrocatechin developers, merely to point out that PMK has few disadvantages compared to them.
Incidentally, and not related to the original poster, "pyrocat" is the name of a series of formulations using pyrocatechin aka catechol aka catechin (which are all the same developer). I'm not sure, OP, if you were talking about one of these formulas or if you were talking about pyrocatechin.