From recent research my DH has done into the brain  - it's apparently been reported lately that 10 minutes on one subject, a quick break and 10 minutes on another subject works best for MOST humans - anyone.   So I believe switching subjects - or taking breaks is the way to go - and I've heard positive things about many ED and LD people finding comfort outside - so outdoors - and extra oxygen to the brain - always a good idea. Spend time around trees! 
Sorry you are facing this situation. I know I could be in it myself in a while.  Our doctor said that without treatement ADHD may well cause a decline in DS's performance. However, also trying to read that book on Misdiagnosis and paying attention to Dr. Ruf's site and the over prescription of medication for ADHD -as maybe our kids don't have it at all?     I've wondered too how their performance is affected if you give them medication that affects their alpha waves -  or brain in general ....when perhaps that's where their genius is coming from?
Has anyone on this site collected articles/resources together regarding Misdiagnosis and/or advoacy attempts - perhaps successful ones regarding allowing a child to type instead of write? It seems a LOT of parents are having this issue and if your child hates to write of course they will hate 3 hrs of work! I keep thinking it would be easier for us as indivdual parents to lobby the schools - if we have a collected body of success stories/articles/ to give- to the schools, to the parent advocacy groups working right now with WAshington etc. 
Anyone else feel a need to divide up the current resources section on this sight into more "manageable" chunks / topics?  I would need to spend a little more time there analyzing it myself - but I don't think this has been done yet.