Well I do have some experience dating younger guys but at most, they are 2 years younger and are quite mature for their age. My fiance is 1 year younger than me. I also an experience whereby a guy 6 years younger than me tried to ask me out but of course I did not agree because.... it just feels wrong when I'm working already and he's still in high school.

Personally I have no problems with couples who have significant age difference, but for myself, I don't think that I can date someone significantly younger than myself.