Hmmm, this is a tough one. I personally think I would have less trouble than some standing up to give my life via execution to support a cause I believe in because I have lead a satisfying life. One who has had less satisfaction in life would probably be hesitant to give it all up, though perhaps they would be more inclined to die since they in theory have less to live for, since their life is not as fulfilling.
On the other hand, I know that for some, having to sever all ties and move somewhere that required essentially a clean slate, start completely from scratch would be unbearable. But for others, myself included, it's a sucky option, but it's also plausible. If you consider the alternative i.e. death, perhaps the strength to move on and the will to live would outweigh giving up everything. You would have to deal with knowing that in your "former" life you were regarded as something of heretic/traitor/or what have you, and that that is most likely the most prominent memory that people in your former society would have of you.
Seeing as how many people prefer the witness protection program to not testifying against a superior and taking the heat themselves (which I don't think would inlude the death sentence - I believe that only lesser felonies make one an eligible candidate for the WPP), seems they would rather take this route, though granted this is a pretty thin comparison.