but redshirting where I live is mostly kids with summer birthdays. My DD with a May birthday is one of the very youngest in her grade, because no one wants their child to be youngest. People with kids a couple of weeks off hold then back, then people with a kids a month off, and then 2 months, so now, having a kid with a May birthday start is starting really young *where I live.* I don't think it's ideal for children to be either the oldest or the youngest, so parents whose kids fall right on the line have a tough call. If the parent lived in my city, my answer would be "dear god no, they'll be way, way way younger than their classmates." But she's someplace else.
I wondered about this. Since the OP lives in a school district with a policy and a process for early entry for children near the cut-off date, it's possible that it's typical for a fair number of children to be on the younger side - at or below the cut-off date. With such a process in place, maybe a lot of parents take advantage of it - as opposed to a district where parents have to fight for early entry or there is a lot of red-shirting. The existence of a formal policy suggests that the district recognizes that cut-off dates are arbitrary and don't really address the individual development of a child. It also suggests that the kindergarten teachers may have experience with younger children in their classes. That's actually encouraging, compared to districts that don't recognize that early start is appropriate for some children.
That's all speculation though. The best strategy is to visit the kindergarten class, observe what is expected of the students and discuss with the teachers their perspective on children who start a little early.
Another thought - OP, if your ds had arrived a couple of weeks early, you would have a different decision. Would you think he's a good candidate for red-shirting or would you just accept the cut-off date and send him to kindy? If you would be inclined to red-shirt, then maybe your instincts are telling you that he should spend another year in pre-school. Good luck with the decision.