G-onset in the T-45 is fairly gentle in my opinion....it doesn't load up nearly as fast as the T-34 (small swept wing vs large straight one essentially). Pulling g's is definitely an acquired skill. Even being out of the cockpit for a while, or being in something like RIs, I lost a lot of my G tolerance. Granted, it only took a flight to come back since my body was used to them. If you've never pulled G's, it will take a little while to come back. In the -45 you get to pull G's quite often. All through fams there are several 4G manuevers, but on your solo, you're limited to 'common sense' for the most part. I've been pulling 6 recently on the tail chase exercises in cruise forms.
The -45 has a g-limit of +7.33 above 5k and 6.5 below it. It's negative limit is essentially -2.3, but you don't often use negative g's except to unload and get some smack back on the jet.
honestly, when I'm the one flying, I never have to hick or really do anything to resist the G's. I think b/c my body knows when they are coming and that I'm doing it or somesuch... no idea. The only time I've had to hick is when I was trunking an ACM flight and we pulled 6.5. Since, I've pulled that and never had to hick, but I've been at the controls.
but remember, g's affect people in different ways, so your mileage may vary.....