Thank you for that list, that was very helpful.
As we live in Europe, the IAS won't come into play - in fact the whole process would be nothing as standardized and sophisticated. Parents can request acceleration, the teachers' conference can grant it if they feel the child shows the maturity and achievement to succeed in the higher grade. The first semester counts as trial period. No standardized testing required or even generally requested, let alone administered by the school! So, it all comes Down to the teachers and principal.

I know the school has grade skipped children in the past and is generally open to it, in fact it was explicitly mentioned as an option by the principal after they had met DS7 at orientation day and heard him read. The question came up again at the beginning of second grade, when DS had meltdowns in the morning over stultifying revision periods! but the teacher and I agreed that he'd just found his feet socially, just overcoming his many anxieties....academically, sure, he'd be just fine....she said she'd also offered to send to third grade for single subjects but he refused to go due to anxiety. Of course, I know all the research and just how beneficial a skip can be and that kids tend to do so much better socially that one thinks, and I never know just how much I am projecting my own negative experiences. Possibly a subject for another thread...

Still, as far as math and science are concerned, DH points out he'd be just as under served in fourth grade as in third, ditto for reading and drawing, and for everything else involving motor skills such as writing, PE and crafts and socio-emotional development he's probably just right being the youngest in third. So, if anything, we'd bring up a skip directly into fifth at the new school.

But as I still don't know whether I want even that, I am still really conflicted what to ask for - try to keep him happy for another two years by going wide and deep? Or try to prepare him for a successful skip by compacting and telescoping? Or let's just let him show us where his development is leading?

Has anyone experience with radical acceleration for a kid that is Struggling with anxiety and self-regulation, among other stuff? I know that at this point, DS would point blank refuse (probably even have a meltdown over it), just as he is adamant he wants to attend the school his papa teaches at....

I rarely let his anxiety dictate our choices for him, and usually I am right and with support, he emerges successful. This one is trickier.