I agree with Grinity about the great teacher being of primary importance. No question! The timing issue--make the move now or lose the chance to move--seems to complicate matters though, at least for me.
Any way to find out who he'd have (or even might have) for a teacher at the current school for next year? I realize it's crazy early for that, and they probably have no idea about how they'll divide up the kids. But if you can at least look at his teacher options for next year if he stayed and see good choices, then maybe you don't need to change schools. If all the choices are lousy, then a preemptive move would probably be called for.
Well, that is a good idea. Because one teacher is really mellow and cool, and the other teacher YELLS AT HER CLASS. I've heard her in the hall and just thought, What could be going on? And my son tells me she does this all the time. So if it is the yelling teacher he won't go there.
On the bright side, I'm not sure there's really a wrong choice here. These close calls are times when I think you have to get as much info as you can before you make a decision, analyze it, and if it's still a total toss-up, then you just go with your gut and forgive yourself if things don't go well. If you did the best you could with the info you had at the time, you can't blame yourself. Sometimes you just have to make a decision, put your head down, and go. You may be at that place.
Well, we can always apply through the lottery. And I have a almost 5 year-old applying for K at the charter school, so I have 2 chances in a way. And then older son can always join when he wants to (although they want to go to the same school, I can't see yds in the K at ods's school coloring worksheets. No way, never that again. (!) Unless they are willing to work with us with older ds.
Accepting that I can do the best I can for my kids and still make mistakes has been the kindest thing I've done for myself in decades!

I strongly recommend it.
Good advice. Thank you for your advice! It really helps me think through all of this.

Good advice.