We have been on the GAPS Diet (I'll just refer to it as GAPS from now on) for over a year now. After placing DS (5.5 y.o. now) on the GFCF diet for a year, we switched over to GAPS as a family. We anticipate to be on it for at least another year, with hopes that we'll be transitioning to non-GAPS foods in 2014. We credit the combination of GAPS foods and his therapies to his amazing improvements. He was diagnosed as autistic 2 years ago.
While we saw improvements with GFCF, it was nothing compared to being on GAPS. He used to be a sensory-seeker, and moved about frenetically. After just starting GAPS, he became "still." He sat at the table. He walked. He stood. As time passed, we saw improvements, then saw regressions. At first it was so discouraging to see the regressions, but then we realized that even with the minor regressions, he was still better off than where he started. Eventually we understood that his great progress was often followed by small regressions. Knowing this made things so much better. I'm not sure when it happened, but DH and I had a wonderful moment when we realized that so many of his "annoying" (hate to use that word, but that's what they were) behaviors had disappeared. I can't remember the last time I heard him humming (except along with songs). The stimming is gone. He doesn't break down if he hears loud noises. I can clip his nails and cut his hair. Just this morning we chatted while I trimmed his nails. Oh yeah, he's conversational now too. No more therapies and no more IEP.
We "cheated" a little at the beginning of GAPS by doing a combination of the SCD intro and the GAPS intro. IMO, the SCD intro is a bit more kid-friendly, which made it much easier to implement. Once he was through the intro, we moved to full GAPS. We haven't strayed from it since, with the exception of a batch of macaroons in which I used a small amount of cream of tartar, not realizing it was a no-no. DS didn't eat much of the macaroons, but DH & I did. We also use baking soda to help with the baked goods. It seems we are fine with it.
It is an awfully expensive way to eat, there is no question about that (totally worth it). And if you're not used to cooking a lot of animal products, it may be weird at first for you. I remember when I cooked my first cow tongue... I was mortified and wouldn't even touch it. Now I just use my bare hands to handle it and peel it. I'm finding myself doing all sorts of things like that. Perhaps it might be that way for you? Take it easy on the fermented foods at first, as you may have read, in order to avoid nasty die-off. Oh, and don't forget, pickles are a fermented food! ;)
I'm not sure if you've seen this yet, but this is the video that prompted me to buy my GAPS book:
The "after" video is from a month of being on the GAPS Intro Diet. Janice, the mother, says that they did GAPS off and on, and followed Weston A. Price diet guidelines, but it wasn't until they started with the GAPS Intro that they had these sorts of results. We had the same result with our SCD/GAPS Intro. I highly encourage anybody up for the task to give this a try.