Not sure why Pyro and XTOL would be compared as they are really quite different. Also depends on the specifics of the Pyro developer. I can help you with Pyro and I can help you with XTOL, and yes everything should ultimately be driven by printing characteristics (or scanning characteristics). I know little about scanning though. If you could list the characteristics of a negative that would make it easier to scan, that would help point you in the right direction.