I don't think he is ready for that yet, but I can't pinpoint a reason.
I don't think you need a reason, really - just follow your gut. It may be that he is ready but you aren't and that's fine too. I don't think we have to hurry into these things.
On the other hand, some kids and parents are completely ready and that works as well. Each scenario is unique.
I'd never leave my DS8 alone - he's far too curious and impulsive. DD9 has been left alone for about :30 or so while I've taken DS8 to school on a day that she's been sick. She's not comfortable being left alone for longer than that, though, and she'll be 10 at the end of the year. I'm not worried about it... she'll be ready when she's ready.
