Very helpful comments, as always, thank you all.
We have been focussed on touch typing, thinking it best to learn 'correctly' to avoid relearning in the future (my thinking is sometimes as rigid as his!). I'll try giving him official permission to experiment and see if he improves, or at least likes it more, freestyling. He's been using Panther Writer, lately, and much prefers it to conventional word processing programs so that's one vote for an adaptive approach. It's taken ages (close to 2 years) to get the school to use Panther (speaking of rigid...) and I'm hoping it will improve his opinion of typing.
I haven't ask about pain recently, since he hasn't been writing much at all. It was such a surprise when he made the comment about typing tiring his hands that I didn't think to ask about pain. I'll follow up on that.
As for DCD, he struggles with zippers, laces, buttons, cutting and was very late to ride a bike. He is slow and messy when he eats and slow to dress/change. He is not clumsy, though, runs well and now rides a bike and uses a scooter very well. The psychologist said he was borderline for DCD and handed off to the pediatrician, who concluded that the bike riding had overly weighted the analysis and that there wasn't enough, otherwise, for a DCD diagnosis.
Our last go-round with OT showed such negligible improvement that I totally discounted it. Typing ergonomics did not occur to me. Back to the pediatrician for an OT recommendation to go along with the anxiety follow up. Some days I feel like the ringmaster of a specialist circus!
