Is a meal at a signature restaurant worth it with a child? That is a different question. I, for one, truly appreciate parents who don't let their child stay at the table and scream, but instead take them out to calm down. But, if the parents are spending most of the meal taking the child out to calm her down, is the meal worth it?
Last year at an Exquisitie Evening at Epcot ($185 per person), a couple brought their child who looked to be 6-12 months. We thought, hmmmm, that's interesting. To their credit, the child bothered no one. But, to keep her quiet, the parents spent most of the evening trading her off and walking her around in the reception area. It seemed like it would be impossible for them to enjoy themselves, especially at a dinner with 7-9 courses, each paired with one or more wines and the winemaker and chef discussing each course and wine.
So, I would say that best answer to the question, "should I take my child to a signature restaurant"? is that you know your child best. If your child is going to need lots of attention, going to need to be removed several times, etc., you may be better with a babysitter if you'd like to enjoy your meal.