Welcome, and get that DYS application going!
"Acceleration" might mean subject acceleration and not a grade skip. I'd work through the Iowa Acceleration Scales-- and definitely ask your son to consider what he would like best. My son's a bit on the small and young side for his grade too, and I definitely understand the worries about social maturity, handwriting, etc. Unfortunately I think you may be at the beginning of a long series of tradeoffs, though the reason for the hard choices you will make is of course a blessing.
