I should perhaps make a fuller post about this at some point, but in brief: "Individuals" are in reality quite divisible (pun intended). Quantum Suicide makes sense to me only if you have a top-down pespective on identity that either persists as a whole or is destroyed as a whole and nothing in between.

If you instead view the self as some bizarre arbitrary conglameration of qualia-producing processes (including whatever processes produce self-awareness, however they do it), then the very concept of destruction or persistence must be applied to actually individual thought-processes, and is meaningless when applied to whole people.