I don't have the answers to all of your questions but for comparison's sake, my DS6 has an opposite disparity to yours. He has a 25pt drop between VCI and PRI. He similarly has a Beery VMI in the 2nd percentile, DCD, and confirmed ADHD (we included brain scans in the diagnosis process and as a result we do know for certain that he has it).
However, for mine his processing speed scores are in the 16th percentile....
For mine, his subtests shed light on the disparity. His vision and fine motor issues were impactful on 2 of the 3 subtests for PRI. We are okay knowing that as you mentioned, it is likely an under-estimate. I find that looking at his achievement testing where his math scores are significantly above what was predicted based on PRI to help illustrate how this gap affects him. We also see it in gaps in his math performance... time, money, geometry, and measurement bring lots of errors while calculation is very advanced for example.
Did you also do any achievement testing? Do you have any other data points to shed light on these results?
I think with 6yr olds, we are only really starting school and the answers to how they are affected will become more apparent as time passes. I know I feel impatient to have answers and solutions now but some things will just need time to figure out.
Hopefully someone wiser than I can shed further light on the scores you have shared.
