I like your point. I think I would accept such an offer with a greater time span, if N was > 1, if I knew how long I had and if I could be with my copies.

1. The psychological stress of anticipating dying wouldn't be worth it to me for just N=1
2. Not knowing when that one would die (only that he would) would be too psychologically stressful to be worth it.
3. The one of me with an expiration date would live his remaining time differently than those who kept going. The ones of me who kept going would do things to honor him and fulfill his needs. The doomed one would expect them to do this.
4. For longer expiration dates, we collectively would need greater compensation (more copies) to make it worth it.