This, finances, and the fact that I'm a very low risk for salvageable death right now are the reasons I'm not signed up (I may also have a lower p for it working than others). I have found that if you talk about it jokingly at first "Hell yeah I want to freeze my brain. I want to see the future! You should totally come with we can fly around with jet packs and see other planets it'll be crazy romantic" makes it easier to bring up seriously later. Maybe you'll just seem quirky rather than weird.

This approach had my girlfriend comfortable with the idea, though I'm not sure what would have happened if I had actually signed up or if she ever would have.