We've done tons of testing over the years, both privately and through the school. Of the ones you mentioned, I know did the ADOS and the ADI. Those were quite a longtime ago, since DS was diagnosed right around his 3rd birthday and now he's 10. I remember that back then the ADOS was considered the gold standard for diagnosing autism spectrum disorders. However, it was known to sometimes miss higher-functioning kids. I know it has different modules for testing individuals of different age groups and verbal abilities. I don't know how the newer revised version differs from the original that was used with DS. I remember we did the ADI with the psychologist, but I don't remember anything specific about it. There were so many specialists and so many discussions about DS's developmental history - they all run together after a while.
I did did not allow any intelligence testing when DS was very young, not until he was 8. At that point they did the WISC-IV. I waited due to DS's difficulties with verbal language, which I knew would cause difficulties with getting an accurate test result. It still did cause problems with testing at age 8, but the subtest scores gave us better information than the full scale IQ.
Gena
DS, age 11 and always amazing
“Autistics are the ultimate square pegs, and the problem with pounding a square peg into a round hole is not that the hammering is hard work. It's that you're destroying the peg." - Paul Collins, Not Even Wrong