We've had the same experience as many others report. No dining plan for us - we use TIW. Our two older boys are pre-teen "Disney adults" and many CMs at TS restaurants actually offer them both menus. I have also ordered from the children's menu, ordered appetizers as my entree, or split an entree with one of our kids. No problems with any of these things. Of course, at a fixed price meal (Ohana, Garden Grill, Chef Mickey's, Cape May) anyone over age 9 pays the adult price - but that's fine - it's the price of the experience and it's worth it to us at certain restaurants!
Actually, I find ordering light is more acceptable at Disney than most other places - my husband and I just returned from a short trip to an all-inclusive in Mexico and they looked at me like I was a little crazy when I would order appetizers instead of entrees, skip dessert, etc.!