I live in the Rochester area. Both my boys are in full time day care and I use a religious exemption for them. Some one I know has children who attend public school in BUffalo, and used to attend school in the Rochester area. They used religious exemptions for both of them as well. What I would suggest is definetly having a lawyer proof read your letter, one who is an expert in this area. I found one and if you need, I can proved his contact information. I have to other MDC mamas before. It cost me, but IMO, its worth it.
I think NYC is harder to get an exemtion for, their laws are a bit different then us in Upstate NY.