IF your son still isn't talking (still has apraxia which too often is a big part of autism), he is not "very mild." Your son should be having speech every day. My son learned to speak well because he had speech starting even before he was two. Now he is very verbal, but it took until he was 4 1/2. Even if your son were the mildest of the mild, trust me, Autism Spectrum Disorders (ASD) kids need Autism Spectrum Disorders (ASD) help. The hyperactivity is part of Autism Spectrum Disorders (ASD). My own Autism Spectrum Disorders (ASD) expert doesn't even call it ADHD--he calls it part of autism. It's completely up to you, but I think the autism needs serious addressing before things will get better, not the ADHD. I agree with the poster who said that once the Autism Spectrum Disorders (ASD) issues are address his attention span will improve. My son was once so hyper he used to literally hang from the chandeleirs. Now he is almost docile. But it happened BECAUSE we treated the Autism Spectrum Disorders (ASD). Again, totally your decision. Just my .02 from experience. The older the kids get, the more you see their social discrepencies and how they really don't learn social cues...and then they are really in a mess, very lonely, and unable to figure out how to fit into a "typical" world. Kids on the spectrum usually have very few friends by the time kids develop deep relationships (like around 9) because it is no longer playing just to run around the playground or make silly noises or swing together. It's conversation, give-and-take, imaginative play, mutual interests. You don't want your son to be one of those lonely kids. I've seen it and it hurts. Good luck 
