I've spoken with PE on phone and via email about doing a few experiments having to do with determining the effects of temperature and time on film results, I figure that I'll use a couple different types of film, as to make sure the results between them are fairly consistent. From the graph that PE had posted, it seems that DK50 and D76 have the most different lines, so I will use each developer at different temperatures and times with a a step wedge of known densities (IE. a stoufers step wedge). I will measure results with a densitometer and post them on here, if people are interested, I'll even repeat the experiment uses developers with differing developing agents, IE. pyro and paraminophonel and glycin developers.