I've seen a few stories on this coach, first off, he has like 100 different onside kick plays, everything from pop ups to drilling the fattest kid in the stomach with the ball. With the KO rules in the NFL and the easy in which kickers get touchbacks, I doubt the onside everytime would work well in the NFL. Plus of course, you don't have that fat kid on the return team. Everyone is a great athlete in the NFL.
As for punting, the odds are with him on that, even in the NFL. BUT even this guy, punted once last year, they were facing like a 4th and 30 from their own ten and he quick kicked.