I felt compelled to add my :twocents: since I'm the mother of a 3yr old.
Up to now, I've kept my child in the cry room, but I have tried as of late to "acclimate" her, if you will, to the sanctuary, extra seating room, etc. These are my personal rules as a mom: If she squirms around in the pew, or won't sit still in the case of chairs, I let it go unless it's just ridiculous. If she starts talking, I answer her quickly and then tell her to pay attention. Sometimes I give her gum; this helps a lot with the talking. One Sunday she kept trying to jingle my keys, and without a word, I firmly took them away and set them squarely on my purse. She left them alone after that. The only time I would consider leaving with her and giving a time-out is if she's acting like a crazy person / completely disrespectful.
The way I see it, if you are at least making an attempt to discipline your child and somebody still has something to say about it, then that's rude. The person making the comments needs to see that you're trying to correct the situation and should be quiet. If you don't try to do something about it as a parent and the said rude parishioner "beats you to the chase," then the best thing to do is to forget about it and try to do better next time. Good luck in the future, I know I always need it.