Sorry for the silence -- I had a sudden bout of something called "real life," that got in the way of the virtual one!
Appreciate all the feedback, and sorry for the lack of clarity in the setup.
In the situation I'm talking about, while I start the immelman the opponent is either heading straight (a la the HO, which misses as I immel) or noses down slightly as if to merge -- but continues with that slightly downward path straight forward. Once he sees that I've gone above him, he pulls back and tries to get nose on, 12 oclock on me again. His path is a much larger curve, but he often maintains enough E to zoom into shot range (much to my "I just died to a dweeb move" frustration).
As for plane matchups, I tend towards E-efficient planes just because my instincts are more at home with E concepts than with anticipating angles. Lately I've been flying F4Us almost exclusively. High wingloaded enemies dont pose me much trouble in this situation, simply because at these speeds energy retention puts me so far ahead situationally that even
I can see what to do. So, the question I posed was looking at energy or E/TnB transitional type fighters, whether Ponies or Yaks or La's or F6Fs.
Bat: I think I do tend toward the energy conservation side in Immelmans, rather than working hard for angles.
Thanks for the advice and suggestions. I'll post more later, when real life cn move into the background where it belongs!