I say go for it! Carry extra snack stuff with you incase she doesn't eat, and then gets hungry after the meal, and enjoy!
We just returned, and did 2 character meals with DS2.
The first was Chef Mickey for breakfast. Unfortunately he isn't much of a morning person, so was a little cranky, and didn't eat much. But that isn't anything unusual for him in the mornings. He finally warmed up to the charactere (Mickey, Minnie, Pluto, Chip & Dale. Didn't want much to do with Goofey before we sat down).
The second was lunch at the Crystal Palace in Magic Kingdom. This time I think he ate more than me (guess he was hungry from not eating much at breakfast or morning snack time). He was a little distracted by the characters (Pooh, Piglet, Tigger and Eyor) but had a blast. He ran up and hugged every one of them. We did prepare him ahead of time to let him know how big they would be compared to him (showed him pictures from his last trip at 7mos, watched the planning video a couple times and pointed out the size difference between the characters and the little kids visiting with them, that kind of thing). Other than his usual grumpy self in the morning, he loved seeing the characters at the meals, and just around the park.