I love the idea. The site needs more to it though, it feels kind of "shallow". I know that is not very good feedback, but it kind of comes off like "different/odd" instead of designer.

But all of that is not what causes me to hesitate...

My current signature is basically a big stylized "B". It works, it's kind of unique and it gets the job done. It's also on my drivers license, passport, 2 mortgages, my checking account (not that I write many checks) 3 credit cards, a hundred + legal documents and probably a few places I'm forgetting. So, I pay you $30 and I get a new cool sig. Sweet. What about the last 20 years of accumulated signed cruft that my fancy new sig now no longer matches? It wouldn't even be a slight derivation from what I have now, it would be totally different, might almost look forged. How do I handle that? Some info/advice/etc on your site along those lines might help...