What AKWarp and Fester Said!
This was one of my biggest complaints since AH came out: the G blackout modeling is really bad. I too used to fly Pitts S2 aerobatics and had no problem at all sustaining 5-6 gs with no blackout tendency at all. Even rapid G onset during a square loop was no prob. Oh, maybe a little gray after 20 min of "head-banging", but never a blackout vision condition. Now, I'm only 5'9", and lift weights and run, etc., so I tended to be a little better off than the big guys, but I don't recall anyone I flew with having any G-LOC problems.
HiTec and the gang don't seem to realize that young pilots who are "G-tolerant", i.e., they do it everyday - like in WWII, can REALLY pull the Gs without problems. This 4.5 G blackout is why I don't fly AH much at all, in fact, I was getting ready to cancel my account when the price dropped, so now I just screw around on occasion.
The blackout should be moved up to the 6g level as a minimum.