Any reason I shouldn't sign up right now? edit: Signed up. Half off for life is a sweet deal.
As written in another comment ( https://news.ycombinator.com/item?id=13447493 ), one has to give away too much personal information without clear reason. I would suggest to use https://posteo.de instead. They offer anonymous payment by post (I'm just a happy user).
I give away my name and credit card info to plenty of websites. That won't help someone crack my private key used for lavabit any easier.