At MGM, we were very disapointed with Starring Rolls limitations on using the dining plan - the cashier said 1 pastry and a drink, for a CS meal, that's got to be wrong but I didn't have the strength to argue so we paid out of pocket and shared a few pastries. When we were there (Sep 8th) we planned to try the abc commissary for breakfast CS but it was closed for refurb.
For lunch at MGM we were pleasantly surprised by backlot express - it's between Indiana Jones Stunt Spectacular and Star Tours - we ordered burgers and fries, pretty standard stuff, but there were several grilled sandwiches that looked very good. I didn't get the grilled veggie sandwich but I wish I did. Instead I went to Studio Catering because the menu looked good and tried their lamb Gyro, it was terrible!!! I love gyros but this one was just BAD. There are pictures of all of the food on the sign above the counter and nothing looked good.
So, for MGM, I'd definitely go back to backlot express - we're not talking gourmet, but for counter service it wasn't too bad and there were a few other choices besides just burgers.