From the title of the post, I thought it would be about how not signing up gives you certainty. I've read someone who doesn't want to sign up say that dying in a normal way would give their family peace of mind.
In terms of whether it's a benefit, if it does motivate you then it's a good Dark Arts way to stop putting off signing up. However, cryonics companies changing their image to take advantage of it strikes me as a really bad idea for the reasons in Ander's post.
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?