I can't tell what the product does. Maybe the extra-simple approach works for dropbox.com, but you'd need to provide more information when the only next step is to ask users for an email address.
After the signup I don't feel comfortable to share files, even test files, with the founders. My inner fear is they'll message me while I just want to test out the product in private. It has the feeling of a shop clerk following my every move when I try a new product.
I'd vote for the older version except making it a bit simpler, remove the first stock picture of the girl on computer, and skip straight to the screenshot.
P.S, your product is pretty much standard functionality that basecamp provides.
'What we like' and 'what works well' might be too different things. This sounds like a good case for A/B testing. Tools like optimizely.com make this very easy.
I think the old version would be better, on the condition that you remove the first "slide"—It's the first thing I see and it doesn't tell me anything about the product.
After the signup I don't feel comfortable to share files, even test files, with the founders. My inner fear is they'll message me while I just want to test out the product in private. It has the feeling of a shop clerk following my every move when I try a new product.