After several months of preparation I just went ahead and asked my dd if she wants to be there (I figure she's a person and is old enough to have a say). She looked at me with the most offended expression and said, "yes, I want to help the baby be born!" She is completely convinced she's going to help daddy catch the baby, or, in her words, daddy is going to help HER catch the baby!

And so long as she okay with it in the heat of the moment, that's just fine by me!
Kids are just naturally in to this stuff. If your dd expresses a want to be there, I say go for it. I do think its important to make sure someone is there to specifically attend to the needs of your child, I'm having my sister for that. People/family totally don't get why I'm letting her be there either. Strangers keep trying to give me advice on "introducing" the siblings... I just kindly say, "yes, well, we're having a homebirth and she will be there when the baby is born, infact she's planning to help catch the baby." The looks on their faces are priceless. I really don't care what people think, but family is deffinately harder, esp since they're planning to be involved in the birth. I wish I had more advice to offer, but really, just know that you ARE doing the right thing. Let her decided. Birth is a wonderful, family centered event.