We have not done ABA but knowing what my son was like at that age, and what he needed most, I will add this one caution: don't allow the perceived need for therapy to override your child's other needs, which include time one on one with the people who love him, and time left alone to pursue his own interests.
I cannot imagine forcing my child into 40 structured hours a week; he would freak out over it. All his gifts have developed in the time he has been free, and those gifts are his tickets to being independent as an adult. Plus, he has always had self-calming routines that keep him emotionally stable; without the ability to pace for an hour, for example, he would be more inclined to meltdown.
I realize it is a totally different situation if you have a child that you fear may never accomplish even the most basic things, like communicating what they need, but those kids still have needs, and I believe that you get a window on what those needs might be when you look at children on the spectrum who can and do communicate.
Which kind of all adds up to this for me: don't chuck your parental instinct, and your understanding of your child and his unique needs, out the window based on a guideline developed by someone not living your child's life. Choose the level of therapy that seems to suit your unique child best.
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).