It's a hard one... schools get so focused on "behavior." I like the idea of keeping him in pre-K and trying a grade skip later if it's warranted. You might also check with the kindergarten to see if they are willing to differentiate academically--then he could stay out year for maturity, and come into an environment that will meet him at his skill level.
I have friends whose kids have had a hard time with behavior expectations- it can cloud the entire school experience if they are constantly in trouble. They can come to see themselves as "bad." It takes special, skilled teachers to help kids meet behavioral expectations without inadvertently hurting their self-esteem.
My DS did alright in kindergarten, but had a hard time in preschool. There was one teacher in particular who seemed highly frustrated with him, and with me, because of his behavior. It caused DS and I both a lot of anxiety to the point where we moved schools for a fresh start.
