Response to Why not make FULL use of chromogenic B&W film?

OK. Let's see how uninformed I am.
PMK works by generating brownish oxidation byproducts during development, in almost exactly the same way that chromogenic couplers are turned into dyestuffs in colour film. Most developers do this to some extent, but Pyrogallic acid has a stronger oxidised colour than most. Pyro' also has a "tanning" or hardening effect on gelatine, with the result that the developer byproducts are trapped in the emulsion in proportion to the density of the silver image.
So far, so good; but what we end up with, is a dye image that is dependent for its density, colour and stability on a lot of variables. The thickness and pre-hardening of the gelatine used for manufacturing the film; the freshness of the Pyro used in making up the developer; the pH and duration of any stop bath; the pH, duration and freshness of the fixing bath; the duration and temperature of the wash given to the film after development; and finally the storage and light exposure of the developed film. Any variation in one of these parameters can, and will, alter the result, making process control just as tricky as with C41, except nobody tries to operate a C41 line manually.
Any process that has so many variables, some of which are outside our control, cannot be called reliable.
The very fact that the Pyro stain exists at all shows that all of the developer products haven't been fully removed from the emulsion. This can't bode well for long term permanence. Which is why there are probably as many ex-users of Pyro as there are users.
By dilletante, I meant someone who could afford to waste time ordering and making up raw chemicals, or kits only available from one supplier, and someone who could risk the ocassional unexpected result.

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