Leaving this here mostly for myself...

(Whoops! writing this up, I realize I fell for the classic blunder! But I won't share that bit, here...)

Instead, I'll just say that couldn't this circuit be tremendously smaller if they ran <&= or >&=  instead of <&>?

(I mistakenly thought I could reduce that and he rest of my circuit to *only* use =... by assuming that 90% of the time != means >, but then how would I account for the 10% where != means <? Duh. Still, <,=,neither is still fewer gates than this, so I guess that's an improvement)