I've been having decent luck on this Sugar fly. Got in at 0.28 (although I used 2 calendars to do it as there's no native fly market from what I can tell, or maybe just IB crap).
Turns out I'm wrong about SB vs W... What I don't understand is why there's no relief between CC and C. Nobody trades EC - it has no volume and is a dead contract, whereas there's definitely significant volume in London Cocoa. Interesting to note that there's relief between KC and RC (D) here. Good luck if your broker actually recognizes it.