....lot of dyslexia information I've read talks about synthetic phonics being the best method to teach but this is exactly what my son seems to struggle with....
Speaking as a long time teacher of reading, I agree with this and some children do need an extraordinary amount of practice to become fluent. Some still read slowly, but as long as they are accurate that is ok. I do think many of us completely underestimate the amount of practice required. And children don't particularly like practising something aversive.
Finding the right amount of the right kind of practice material is problematic as children get older and more reluctant.
One beginning reader I taught at age 5 was reading over 3000 words per week that I knew about, never mind all the words she was coming across elsewhere. Another child the same age, and we were struggling to get through 100, with all kinds of behaviour designed to wriggle away. Somehow, I believe,you have got to find ways to get the reading practice in,( even if it includes bribery ).
I looked at the Easyread site. I do think it could have provided more details, like a scope and sequence. The number of responses required in the first lesson were not that many, that could of course change as the programme progresses.
You can see exactly what you get with Dancing Bears. Computerised programmes look attractive, but for a poor reader you cannot afford to leave them get on with it on their own. They need adult supervision for the whole thing.