Big fan of mine, it was my second build and it's been a staple on my board ever since. I don't see the need for any other chorus, although I do kinda want a mix knob on it.
Basically it replaces the 150pf cap at C18 with a rotary switch with the values of 330pf, 194pf, 103pf, and 32pf. Basically a depth range extender that can make the chorus effect more flange like. It doesn't introduce a feedback loop.