Has he had an OT evaluation? Our OT suggested DCD for our DS7. His printing is slower than average and I'm guessing his typing will be as well (although we haven't pushed it yet).

Is there a reason that your DS can't use voice recognition? This was suggested for my DS by the school resource teacher. So far we haven't really given either typing or voice recognition a try - he's only in grade 1 and writing demands are not too much. But I imagine we'll need one or the other in future.