RE: Hitec servos and jet models...
I can't answer for both, but I can attest after running numerous tests that the Hitec 5645 is just about the worst servo I have ever seen when it comes to centering on a control surface.
I had bought a few of them a few years ago, and ended up using them as retract servos in my models till I was out of them. And it was questionable to me even in that application, I should have just thrown them away.
FWIW.
Sean