Very rarely come across 'no' voters and those that I do come across are generally pretty soft. Meet a few hard core 'nos', but you have to expect that.
I think we'll do it, based on the fact that the current yes vote is pretty solid and a good number of no voters are saying no as a default. Once the facts come out they'll begin to shift, as will the don't knows.
I heard a figure the other day. Not sure if it's true, but two weeks before the Quebec referendum the no vote was sitting at 60%. It ended up 50/50.