I am sure there is some accurate formula somewhere that shows the HTC has it right, but it sure seems like what you say is true and almost certainly tied to certain aircraft.
It appears that the decision to choose certain aircraft, also trains your pilot / upgrades pilot G suit.
What I have noticed and can replicate very easily:
Once a pilot has blacked out and regains consciousness, he is more likely to black out again with even less G forces at work.

Anyone want to debate that?