The Tweet didn't mind zero G at all. We had the "180 Club" on our G-Meter. Pointing straight up was 6.67 g's, and straight down was like -2.67 g's. We would do both on a flight...and hence....join the 180 club. Outside barrell rolls inverted are not cool nor fun.
Unloading also cleans up the jet. If you are doing any type of maneuvering, inevitably Mr. Computer has the flaps and slats programmed out, maybe a little rudder toe in or out here and there. Unloading fairs everything, hence cleaning up the jet and giving you pretty good instantaneous acceleration.
I'm not sure how T-6 land was, but T-37 land had 2 Majors that I could remember that were both OCF guys.