Guess I'm late to the party but I've been enjoying reading the responses to Phil's challenge while I waited for an opportunity to see Zeta Cancri for myself. It appeared as a creamy white double at low power. Zeta-1 appeared elongated at 163x and 198x and was resolved (according to David Knisely's definition posted above) at 326x. I suspected a notch at 244x but had to go to 326x to confirm.
It might be cheating to use a 14" scope, but the seeing wouldn't allow me to go any higher to see the split. In brief moments of settled air I thought I could see the split at 355x and 391x but it might have been averted imagination so I didn't include that view in my sketch. The seeing made the stars appear somewhat bloated at higher magnifications.
Thanks for the challenge, Phil! This is the first time I've looked at Zeta Cnc. Btw, I have the 3rd and 4th editions of Starware--it's a very good reference.