I have to agree on the cursive showing a much better return on investment of effort. We started OT just before DS turned 7. OT said it was pointless working on printing and moved straight to cursive. That said our experience was similar to PBs. He did go backwards when we took a break over the summer. We only worked with the OT for about 6 months and that has given us, as PB said, much better posture, less wrist pain etc. Our OT said she didn't think she could do much more after 6 months, it was really just a matter of practice.
There's certainly no harm in starting typing now.
The big improvement in DS's writing has come with medicating for his ADHD. Beforehand I'd poo poo'd the idea that it would improve his writing but I've happily been proved wrong. Having looked back at your earlier posts this doesn't seem to have been the case for your DD though. DS will actually just go into his room and write now with no prompting. Turns out he's quite the poet!
A mechanical pencil does wonders too.
