We have been in a pattern since the summer: 1-2 weeks of 100% EleCare followed by 4-6 weeks of regular food supplemented with EleCare. The first signs that we need to jump back on EleCare are a skin rash (like eczema) and then irritability and, finally, loose stools. Our boy is mostly happy, but when his bowels are inflamed - he becomes a little pistol. It's our cue to put him back on the EN for a week or more.
It works like a charm for him. The other night, he had lasagna for the first time in... oh.. two years. He gobbled it up and didn't have any issues.
We have some new friends who have begun the SCD recently for their autistic 4 year-old boy to try and clear up GI issues. They (seemingly) handle the day-to-day grind of the SCD better than we did, though have seen only a little GI progress to date (after a month or two). I haven't read up much on the thoughts of the effects of SCD on autism, but it seems that looking at both GI changes and personality changes would be warranted after introducing the SCD. We'll continue to support these friends in their SCD adventure -- hopefully it helps their son in a measurable way.
Finally, we had a scare a couple of weeks ago with blood (maybe) in our daughter's stool. This would be the same exact time/age when our son was diagnosed. Since then, she's been doing fine and I hope she doesn't inherit Crohn's. It's Cyrus' disease! Not her's...