Interesting to speculate, but I would brew small batches and find out for yourself. One other thing to remember within the ale yeast spectrum is that the ale yeasts already don't metabolize some sugars that lager yeast will do (and some Brett strains will metabolize even more things). You might also want to focus on creating or avoiding fermentability using sugar or other adjunct, for example.
My guess is that in terms of resultant gravities from mashing at different temperatures and talking in terms of different flavor profiles without doing more, the same yeast may react differently to those worts of varying compositions (i.e., worts from different mashing temperatures alone). The next level would be to play with arresting attenuation, once you lock into a particular yeast strain that you like to get a different flavor profile or level of body.
Again, really interesting and thought provoking discussion - even though its an old thread. Heck, if it keeps Dave over here and not over at HBT, it is worth getting into it.