moondog, you can private message for free now....
I tend to agree with justa on this one.
wanting evidence that an approach works is one thing. the SI OT I used for dd1 was involved in a large-ish study, and was passionate about publishing, and opening the whole field up.
suggesting that, because you have no experience of the field, and are not able to find/read/speak to the people involved, that running about in a field and getting some fresh air is a similar thing is, quite frankly laughable, and the equivalent of the whole "just talk to your child more/you must be talking too much and not letting your child get a word in" crap that is often spouted by shite SALTs (I do know, btw, that there are, of course, parents where both these ideas are pertinent)
we used to do SI with dd1. I have written about it before.
the results were startlign to say the least.
dd1, overnight, and form her very first session (bearing in mind she is ASD, take s alittle while to warm to a person, and had no idea what was expected of her when she went in. she also went in alone, which was a new experience for her, as previously I had attended therapies with her, for anxiety/insecurity reasons. I could not, however, expect dd2 to not climb/jump about/generally distract dd1, so had ot sit elsewhere with dd2)
so, before SI, dd1 was a bundle of anxieties and sensitivities. Noises were a problem, as were people (as in in shops), waiting, listening/hearing when stressed, along with a couple of major phobias.
To put it into context, the week before we started SI, we went shopping, as we oftne do at a weekend - dd1 enjoys this, although it used ot be extrememly stressful fo rher (she enjoys haivng lunch at a cafe, so that is why she is so keen 
)
dd1 hated the noise, had her fingers in her ears the whole time. she couldn't attend to anyhtign we were saying, as she was so over-stimulated. she was bothered by the escalators (she is phobic), and couldn't listen to us when we told her we wouldn't use them. she dropped ot the floor, or refused to walk past, or both. had to be carried past, still struggling (she is a very tall 6 year old. this is not easy). she couldn't/wouldn't wait in any shop, either to let us browse stuff (by browsing I mean choosing between 2 items, maybe taking up 2 minutes) or to wait in the queue to pay. either dh or I had to take her away, and keep her constantly moving (an example of your "more exercise" not working, md) - pausing even for a moment lead to her droppign to the floor, running away, or clearing the shelves of things and dropping them on the floor. she removed her shoes/socks as soon as we waited anywhere, too. so, I had ot visit the phone shop - she took off her shooes/socks, and ran around the whole time. fiddled with everyhitng. was typical demon child, tbh. had a meltdown when asked ot put shoes/socks back on.
the following week, we were back again (gluttons for punishment, us ). the only difference was that on the Friday, dd1 had had her first SI session. "just" some swinging about and softplay type stuff.
this time, dd1 walked calmly around the shopping centre (same centre, so not a sensory difference/acoustic issue). she listened to directions on where we were going next - eg, past the stairs, into the shop with the blue sign type directions. she paused and stiffened when she saw an escalator, but listened when we said we wouldn't use it. we gave her the choice of "coming up" to go past - she chose to walk, and did so calmly. whenever we had to wait to pay, she sat down by our feet, and waited calmly. she didn't remove her shoes or socks.
honestly, the only difference was the SI. the first description had been our reality for months, if not years beforehand. we carried on doing it, becasue, tbh, dd1 was every bit as draining at home, and at least we got out and about a bit. and she did truly enjoy lunch out. just one session of SI made such an enormous difference to her, and she was able to cope with an awful lot.
yes, it does appear (to the uninitiated) to be "just" softplay and bouncing around. but it si more sophisticated than that. eg taking dd1 to the park (which we do, regularly - we are outdoors a LOT, and she participates in a lot of activities, eg trampolining, horse riding - stuff that gives good sensory feedback anyway) means she gets some exercise. taking her to SI meant she got the exercise, as well as working on her core stability muscles in a cohesive way - there is an OT part to SI too. me plonking dd1 on a swing at the park, and making sure she is safe, is not at all the same as dd1 going on a swing at her OT session, where she is totally safe as it is a platform swing, and set up so that she can get it moving and sustain the movement - using the same principle as the sit'n'move cushions - total body involvement in balancing and correcting her moves. she then had to work on co-ordination issues, and eg collect a beanbag form the opposite side (ie use her left hand to reach across to her right side - working on midline issues) to throw through a hoop at the appropriate time, while also working on langugae issues. a real holistic approach, and not somehting that can happen in your average park. some of it can, but not to the same level, hence my earlier comparison wiht SALT.
what dd1 now receives as SALT - a solid approach, working consistently towards targets, is a far cry from "well, read her some stories, she'll soon pick it up" - the usual bollocks spouted when SALT issues are first raised. what dd1 got form SI was a far cry from what she got at the local park/softplay/walk in the woods.
her receiving SALT at school does not mean I no longer read to her, or sing with her, or indeed work on any of her language issues. just her her attending SI does not mean that we no longer play in the garden, go to the park, or indulge in any OT type activities like squashing her under the sofa cushions at home.
Si is (or certainly should be) delivered by OTs. It is a branch of OT. suggesting that SI has merely been invented to rip off parents desperate for a "cure" sounds an awful lot like the crap I get told by my LA about ABA (and yes, I do know the difference is that ABA has a solid research base) - they too talk a lot about how much it costs, and how many parents are disappointed by it.