One of the counter suggestions I've heard is that "energy retention" should be a test of deceleration from 500mph to 400mph in powered, level flight. The only problem is that some aircraft break apart long before they reach 500mph ias.
What the glide test tests is manifest in actual combat. You've showed me as much yourself with the way you make use of the Ta-152's energy retention. It's probably the most difficult performance trait to make use of in the whole game.
Yeah, I realize difficulty getting to a top dive speed testably higher than the top deck speed of the fastest is a problem for some airplanes.
Just a thought:
In a practical sense I suppose the question we are testing is whether a an airplane with a lower top speed following another in a dive, lets say to the deck, can hold position actually gain for long enough after leveling out to perhaps gain a firing position. Say an F4U vs. a P-51.
Or, another possibility, can the airplane with lower top speed but better E-retention gain significant separation after leveling out from the dive? Say a P-51 vs. a D9 with the drop-tank rail.
That idea should perhaps shape the tests.
EDIT: Another thing to keep in mind: Halve the available thrust for Moot's Ta-152 and the power-off efficiency of the airframe wouldn't mean much in combat. Double the thrust for a Hurricane and its draggy airframe wouldn't mean near as much either. So.......