PMK is a great developer. (The P stands for "pyrogallol" so calling it PMK Pyro is redundant. ) It's very long-lived (up to a decade) so it's great for an occasional user.

When you say you want to experiment with pyro, you have to decide what you mean. Pyro traditionally refers to pyrogallol. There is also pyrocatechin (which many people call catechol or catechin) which has some similar traits but not identical. Both are staining developers. (So is hydroquinone but to nowhere the same degree.) Each has a different flavour.

The Pyrocat formulas seem to be the most respected of the pyrocatechin developers. To be honest, few developers have used this ingredient in recent memory. That is not to say that it's not a good developing chemical - it is. The number of people on here that are happy with the Pyrocat formulas seems to speak volumes as to the quality of them.

I've tinkered with both. I know PMK a lot better, and I prefer it. I can't tell you why. Photography is sometimes a little like that.

I'd recommend you try PMK first, because of its long shelf life and outstanding results, but no matter what, pick one and get to know it first before trying the other.