I have only gotten one note in over twenty years - citing religion. Other parents have also written me notes also, but they have been to tell me that their child will stand. I think some students went home complaining about the pledge and were surprised by their parents' responses. I am student teaching right now. But, my students are made to say it daily.
None are enthusiastic about it, and it seems more rote than anything else.
I have no problem with the students saying it, and no one has a problem with me not saying it. I stand respectfully and face the flag, but I just can't say it. I think I would feel like a hypocrite if I did.