When our son was younger, he was on Metadate, and it didn't seem to be working, so we tried Concerta, Strattera, and Adderall. The Concerta just didn't seem to do ANYTHING -- but having said that, we were working with a general practitioner without much experience with Asperger's, and I am now convinced that he didn't really know much about changing dosages around until the medicine shows some effectiveness.
Concerta would be a good med in many ways, because it's extended version can last 10 to 12 hours -- WONDERFUL if your child needs a little extra help in the afternoons with homework (which mine does need). Metadate only seems to last through the school hours.