Some of these numbers are different from what I was observing (immediately after the release of the turbine) when the Liquid Heat Exchanger displayed 100/100 at max capacity instead of 200/200. That said, the HU/t I saw coming from my reactors didn't change even when the LHX got its GUI tweaked.
I did see a significant drop to 64EU/t from turbines that had been giving me 128EU/t.
Before that, though, yeah, the difference from stirlings to turbines was shockingly low from a level of effort standpoint.