I mentioned upthread that my view of what the typical child knows and when is somewhat skewed. It might be more skewed than I thought. ... so it's possible that I may be in denial

Possible - I would guess, since you are here and human - that it's likely!
I go back and forth between thinking he's just bright and thinking "uh, maybe there is something there." After seeing what the rest of the kids in his K class are doing, I'm learning towards the latter.
A good tester can help you with this and it's a wonderful thing. An even better tester can negotiate directly with the school and help you find a good fit. Most testers will just make knee-jerk statements like 'well you have to send him to a gifted school' or 'well you had better be prepared to homeschool.' sigh. But it still helps to get your yardstick 'standardized' - a lot.
Maybe ask the school which of the local folks they think are particularly good at helping parents understand the results of all that testing. It would be nice if you could just ask directly - which testers will you believe and do what they say?
sigh again,
Grinity
Aside: Lately I've been watching junk TV 'Millionare Matchmaker' and wishing the Patty was yelling at school districts and advocating for gradeskips instead of fixing up folks. It's like I can watch the regular show and my imaginary show at the same time.
((shrugs and more shrugs))
Grinity