Pilots suffer the effects of g because the heart cannot pump oxgenated blood up into the brain in sufficient quatities. However these effects take time to cause brain/sight issues - time and g. For literally a second or two we are OK so the rate of g onset is not a factor just the g you go to and the length of time you are at the high g. In the old days before g meters were fitted in cockpits pilots momentarilly pulled numbers like 10-12 g and so had the wings off in a flash without passing out.
Negative g is a very different matter. Here blood is forced into the head and you can burst small blood vessels in the eyes and brain - not good.