Hi JBDad. We had our DS7 skip K. It was a good decision for him based on these facts:
1) We had already had testing done and MrWiggly had clearly mastered K curriculum, IQ testing put him in the gifted range and out of level testing showed he had already mastered some first grade material.
2) MrWiggly had attended daycare/preschool with a "pre-K" program whose schedule and curriculum was basically exactly like what our school did in K. He had been in daycare from the age of 12 weeks, so certainly had already grasped the concepts of groups, schedules, stand in line, etc.
3) MrWiggly was already having behavioral problems in preschool out of boredom
4) His visual-motor skills were tested at the 99th%, he was self taught in writing but has great handwriting skills in terms of the motor part of the task.
5) We felt that MrWiggly would do much better starting off with a group of kids a year older, as opposed to having to leave a group he had befriended.
6) There were no identified problems with social skills or peer interaction
7) MrWiggly fit in well size wise with the first graders and is only 7 months younger than the youngest "regular" classmate (he's a March bday, with cutoff of 9/1 for the class).
8) Although MrWiggly wanted to play in the K room he also wanted to "learn hard math" and we knew he wouldn't get that in K.
9) The private test report we gave the school stated that he would need "significant differentiation of curriculum" if placed in a K program. I think this clinched it for the principal. He still doesn't seem to want to ask his staff to differentiate anything!

That said, your decision will need to be based on the personal knowledge you have of your son, your knowledge of the teachers he may have in any given placement, the support of the administration at your school and their willingness to meet his needs in any placement you decide on. There's a lot to be considered when looking at acceleration. The Iowa Acceleration Manual is very helpful to use in this matter. It provides a nice list of things to consider when accelerating a child.

Given your description of your son I can't really see how he would be happy and learning in a K program without "significant differentiation." Even in first grade, my son was in the highest reading group and was the best reader. He was never really challenged in reading or math - we ended up pulling him from first grade math, homeschooling the end of the year, then skipping another grade for placement in math the following year. We do not regret having him skip K at all.

If K is not mandatory in PA have you considered just homeschooling and not even enrolling him in K at all? Why not just keep him home and then advocate for differentiation in first. Perhaps that advocacy would be easier? Quite frankly I have to agree with comments that your son may fall in the PG range. In that case, it is unlikely that a typical public school will be able to meet his needs.

Do you have the resources to test privately? Our school would not touch our son until he was actually attending. I tried multiple times to get them to test. They finally agreed to look at our private testing, have the psychologist do some brief testing of her own and then meet BEFORE school started - only after we informed them that we were taking him to the Belin-Blank Center at U of Iowa for testing.

Good luck. It's a lot to consider and a hard decision. Just remember that you can only make the best decision for this moment with the information you have at the time. And whatever you decide now won't be written in stone or the last decision you have to make in terms of education for your son! Trust me on this one!