Most chefs are EXTREMELY accomodating. Since I have horrible food allergies, I make plenty of PS because I really need to know what am I eating is ok for me. I make sure the CM gives me a phone number (along with a confirmation #). Since tomorrow marks a week till my trip, I'll be making phone calls on a daily basis to let the various restaurants know about my restraints. I'm even hoping that this time there will be some desserts I can try.
Be sure to mention your food allergies when you check in and with your server. Ask to see the chef, even if you are at a buffet (cross contamination can be a problem there).
As I said, I have found most to be outstanding. I also give a special thumbs up to Chef Stephan at WCC (for the best breakfast ever -- yes, it's been over 2 years and I still remember it) and Chef Bubba at the Kona Cafe. Chef Stephan told us he has prepared special deserts for diabetics as well as for people with allergies.
Over all, I just want to say that WDW is the ONLY place I feel "safe" dining out. And for the most part CMs at WDW are the only people who truly "get it" when it comes to food allergies.