Hi, I haven't been here for over a month and just remembered I had promised to update my posts on this thread. I had mentioned that after our experience with Feingold my daughter's pediatrician was trying it with her daughters. She is now a believer. Her youngest, who had been fairly easy as a toddler, had increasingly become more and more challenging (breaking things, tantrums, constant sarcasm) and has become a sweet, easy child by avoiding salicylates (as well as dyes and other additives) but for her, like us, the key really was the salicylates and personal care products because we already avoided dyes and preservatives. For her oldest she doesn't think she saw a change.
My daughter hasn't had a fit in almost 2 months. She was previously raging at least 3 to 4 times a week (and by raging I mean breaking things, hitting me and intentionally destroying things) We can go to stores, we can go to museums, we can have fun...and not deteriorate when it's time to go or I say "no." It has absolutely been a miracle. I cook - a lot...but given that I now have a neurotypical child; it's not that bad....!! 
ETA: I think it would be very hard to implement this with a teen. Food and personal care products at home could be managed, but getting a difficult child on board at that age would be very challenging...
