Like any therapy, RDI "works" for some but may not "work" for others. Each individual with ASD has a unique set of skills and challenges. Because ASD affects several areas (behaviour, speech, communication, sensory integration, motor coordination, etc), a typical treatment plan involves several different types of therapies.
We're had good success with RDI (Relationship Development Integration). And this is after 15 years of ABA. I find RDI addresses core deficients of Autism. It's easier and cheaper to implement.
I'm not familar with the tutoring services that you mention.