I noticed you haven't gotten any responses yet.  I suspect that's because this registry is brand new, so there's really no one who has any personal experience with it.  My personal opinion is, if you're at all interested in participating in a research project, there doesn't seem to be a downside to signing up.  Only minimal information is required to register and you're not obligated to participate in any study.  They'll contact you if there is a study that you might qualify for, but you are free to decline at any time.  I presume you can also remove your name from the registry whenever you like.  If you decide to sign up, I hope you'll let us know if you're ever contacted for a study.