Although I do not have experience of doing this myself, as a user I would be put off if I had to do some hunting around to "see what it was all about". When it is so easy to just click the back button you want to let visitors know what they are looking at straight away. Of course this could be different in your industry so A/B testing would be an ideal way to find out for sure - but I would be worried about people bouncing.
How about some sort of hybrid sign up page? - where they are given some landing information before being promoted to enter their details. This could be a good middle ground and perhaps something to include in your multivariate testing.