I think I see part of the clarification in your post: you recommend using one grain for the starter, and have that grain be dominant in the flour blend for the bread. I'll see if this is a viable option and if it gives me better results. I definitely intend to do some further research on which flours cultivate which microflora and see if I can tweak the flavor profile of my sourdoughs accordingly.
Don’t worry about the research part; I’ve done it. About to do a post based on it. I have all the necessary ingredients myself to test some of the guesses I’ll make, but I have little time, as other experiments wait.