Well, to my knowledge \ is intentionally chosen to be symmetric to /, because most (all?) meanings are closely related. Split-join, decode-encode, reduce-cumulative reduce, etc.
Is there a way to get &1 0 1 to behave similar to &1 0 2? that is, I want a way to force the "generate x0 copies 0, x1 copies of 1, ..., x_N copies of N" behavior, regardless of whether every element should get at most 1 copy.
Hmm, maybe it does! I was thinking it was just giving me the indices where the array is non-zero, but maybe that's the same thing as the other behavior...