We had the same reservation time during our last trip. I don't know how or when they start the lunch changeover, but we were there for an hour and didn't see any signs of it. We saw all four characters and participated in a little parade/celebration in our dining area. I think this is a great seating time because you can enjoy the park for the first hour and a half when lines are low and then go eat. Donald's Safari Breakfast was one of our favorite character meals!
ETA: The food stayed "breakfast" foods the entire time, but we counted it as our lunch. We ate plenty and there were plenty of meats and other foods to fill us up. It was not just pastries and fruit.