It's a difficult one really. It's something I'm going to have to consider before too long, but I can totally see why you'd be over-protective.

One thing to remember - despite the big child abduction stories, they are INCREDIBLY rare - statistically a child is way way way more likely to be injured or killed by a family member than by a stranger!

A lot depends on their friends too. If they're all relatively sensible kids then why not let him go out for an hour (at first) and make it quite clear that if he's naughty, or wanders off then he's not going to be allowed out again. Give him boundaries, and a warning that if he goes over them then he's not going to be trusted to go out by himself for a long time.