What a Diagnosis Won't Do
Unfortunately, one thing a diagnosis of sensory integration disorder won't do is get you insurance coverage for the therapy your child will need. Since sensory integration disorder is not yet an official medical diagnosis, many insurance companies will not consider it as an acceptable reason for services.
That doesn't mean you'll necessarily be left to pay for everything out-of-pocket. There are codes and related diagnoses that the person in charge of billing at your occupational therapist's office might use to put therapy with a sensory integration approach into a category that your insurer will find acceptable. These may include developmental coordination disorder, motor apraxia (problems with movement skills), hypotonia (low muscle tone), delay in development (missing milestones), or encephalopathy (problems with brain function).
When looking for private occupational therapists, be sure to discuss the issue of having occupational therapy evaluation and treatment covered by insurance, and make sure your chosen therapist has ways of working that out.
The ability to get therapy covered by insurance shouldn't be your only criteria for selecting a particular therapist, but it should definitely be a consideration. You may find that large or hospital-based practices will offer the most experience in selecting codes that will be acceptable to insurers. They will likely offer other advantages as well.
There are a few other things that a diagnosis of sensory integration disorder won't do:
Cure your child instantly
Give you a specific, easy-to-follow plan of action
Convince skeptics in your family that there really is something wrong with your child
Eliminate the possibility that other things may be wrong with your child
Answer all of your questions
A diagnosis is empowering. It will help you understand your child. It will help you give your child assistance and therapy that will make a significant difference to her. But it's not a magic wand. For some kids, it may offer enough of a solution to bring problems that had seemed uncontrollable to a level that can be managed or overlooked. For some, it will be just one piece to a neurological puzzle that is far more complex. Anything that helps you understand your child a little better and parent more effectively is worthwhile. And in that context, a diagnosis of sensory integration disorder is very useful indeed.

