My son was in a similar situation but coach told him while they didn't have money for his freshman year, he would get money for the next three years. They also promised him that he wouldn't be able to tell the difference between the kids who get money and the kids who didn't in the first year. So far, it's been absolutely true. Son said at Thanksgiving that's he's learned more baseball through the fall season that he would have in four yeas at another school.
I agree with those who say don't second guess it. No matter where you go, all you're really getting is a chance to prove yourself. It might be harder to do at a D1, but at least your son will know that he tried and won't have to second himself later in life — gosh, if I had tried D1, where would I be now???