I agree that it might be nice to transfer gradually, but if you avoid the risk of losing any fraction, then you solve the problem of one-shot transfer also. If you don't solve that problem, then you still risk losing something to treachery. Maybe you could suggest a concrete protocol for a verified-source reincarnation scenario.

I'm also envisioning some non-divisible resources as well, e.g. privileges and obligations with respect to independent entities (we'll assume these were crafted to transfer on reincarnation).