I had lap-band surgery in dec. of '04 and have been to WDW and DL several times since. I carry my surgery card and at any of the buffets, I pay the kids' price. At TS restaurants, I either ask for a smaller portion (that sometimes works, sometimes it doesn't) of the adult entree, or I share with someone in my group (if they're willing)......or I box up my leftovers or DH will eat it!

for me, it just depends on what the menu options are.....at CRT, even though I can't finish it, i'd rather have the prime rib or major domo's pie vs. the kiddie food, kwim??
I wouldn't recommend the "kid food" either. I've never had a problem paying the kids' price except for the times I've forgotten my card (those times I had to pay adult price), so hang onto that card!

Otherwise, I found all the restaurants very accomodating. Once, at the Cinderella buffet at GF, I wasn't finding much I could tolerate, so the chef came out and asked me what he could make FOR me. Very nice!
As long as you're not afraid to pipe up and ask for what you want/need, I don't think you'll have any problems. And good luck on the upcoming surgery!
diana