I would always get it in, i think folding it will more often be a mistake then a good play. Unless ofcourse, there is a lot of ICM in play. In a satty for example, or a double or nothing SNG you may have to fold it. But even in MTT ICM i think its going to be to strong to fold. Maybe live in a closer spot with kings + having some tell, sure. But i don't think KK is a hand to hero fold. Youll more often be ahead then behind even when facing a lot of aggresion early stage. I do understand someone may fold KK very very rarely though, but you'd must have a very good read about a specific opponents rather then just VERY tight stats. You must know your opponents play better then just tight stats.