Well, looking at this from a chemistry standpoint, there are a lot of factors that affect rate, however, for each developer, you could conduct a densiometer study and determine two points on a graph of rate of development (measured indirectly as a gamma, in this case) vs. temperature, and then extrapolate other points on the graph from it, you can also get a lot of other chemistry data from this graph (you'll have to excuse me, I can't remember all of the data that this graph can help you with). After the AP's this year, I'm planning on doing a study on developing agents and their associated rate laws. I'll be happy to let you guys know how that all works out when I get there after the second week of may!