Pyro produces a very nice (and unique) "look" regardless of staining. That is a good objective for a developer like this, and it is a reason not to substitute metol or catechol. With 6 g of metabisulfite, I would think the A bath is pretty close to neutral. That means it probably doesn't have great life, but it should be reasonable. I don't know if making it more acid would help, but it might.