For my sune/antisune idea, I was hoping that with more target states available, all that would be required would be correct choice of a simple insert such as RU'R', RU2R', sledgehammer etc., perhaps with simple semi-intuitive setup moves. It wasn't that simple, so I dropped it.
iMHO the best potential for an LS step is in solving hard F2L cases. If your last slot is going to take 11 moves and a rotation or two to solve, why not learn a few options and do something else useful with those 11 moves too, like solve LL edges? One example would be ZBLS when both pieces are stuck in their slot. The EJLS concept could be extended such that if you encounter a connected pair such as F2L cases 11/12 or 23/24 mid-solve, and solving it would be awkward perhaps because a rotation would be needed, you could quickly insert it as-is, enabling simpler lookahead, and come back and solve it via ZBLS as the last slot.