I get the sense that many of the people who have signed up have done it less for the increased survival chances or the sense of comfort, but as a sort of flag waving. It is pretty good signalling that you are opposed to death and part of the ingroup that is opposed to death. Those little medallions are badges of a refusal to submit to the awful thing.
You'd have to want to signal very strongly to overcome the inconvenience of doing the paperwork and forking over cold hard cash. Self-signalling seems to be a plausible motivation, but I'm not sure how much benefit you'd get from being able to tell other people about it. Not to mention the opposite pressure that most people have because they have to convince their close family members to respect their wishes.
I wrote a blog post arguing that people sign up for cryo more for peace of mind than for immortality. This suggests that cryo organizations should market towards the former desire than the latter (you can think of it as marketing to near mode rather than far mode, in Hansonian terms).
http://specterdefied.blogspot.com/2015/06/a-cryo-membership-buys-peace-of-mind.html
For those signed up already, does peace-of-mind resonate as a benefit of your membership?
If you are not a cryonics member, what would make you decide that it is a good idea?