Phenidone vs metol in paper developers

[varjag]

What is the difference in the effect of phenidone and metol in paper developers? My understanding is that in film developers, phenidone helps with increasing the effective speed, while it is unlikely a concern with printing. So, what are the advantages? Shelf life, costs?

 

[Ian Grant]

Metol can cause Dermatitis, Phenidone doesn't.

PQ devs compared to MQ, have far better shelf and dish life, less prone to oxidation and collapse, slightly cheaper to make up, finer grain so can be warmer toned.

Can be made up as a concentrated solution, Ilford's paper devs are PQ, Agfa Neutol WA (liquid) is now PQ.