Have you considered automated varying memory clock too? (effectively making this three dimensional -- a stack of graphs like you made) I ask because I've read hints that suggest that there exist lower 'sweet spots' of gpu/mem clock that exert similar, or slightly lower hash rate at a much lower power draw.
Yes, this is on my todo list. I just need to find the time to add it. I'm thinking it might be prudent to try to estimate the amount of time it will take to iterate over all permutations of mem and core clock and warn the user if it is likely to take a very long time.
Any suggestions on how to plot the graph in that case? If the number of mem clocks is large, the graph will be difficult to read.