My take on it
Actually, I think its exactly the same as Spock. But I don't think post-Genesis Spock is the same being as the one who died saving the Enterprise. He made a copy of his katra/soul and uploaded it to McCoy's brain (he obviously didn't do a live transfer as he was still functional after the meld. The original katra died in the Enterprise's Engine Room. The copy was transferred to a cloned body. And even then the copy couldn't have been that good because Spock 2.0 was missing knowledge and had to have his mind "retrained" on Vulcan. Sure, all of his friends viewed him as the same person (as did I when I first saw TSFS), but I now have doubts.
is that what defines continous existence/personhood is quantum entanglement. ...
Christopher - Thank you for the well thought out response. I have to admit, I'm not sure I understand all of it, but it sounds fascinating. I'll give myself a change to reread the link to your blog-post you provided and let it all sink in before I respond in full or just agree with you.
Thanks for giving me a lot to think about.
"Canon is only important to certain people because they have to cling to their knowledge of the minutiae. Open your mind! Be a Star Trek fan and open your mind and say, 'Where does Star Trek want to take me now'." - Leonard Nimoy