Turns out 6C>IAD j.D land hjc j.D>j.D is the most stable. If you delay it enough and do the IAD early enough it should work in any spot that you'd actually need it for. Obviously for close 6C you can just DC and it will cross under.
Okay, DJ, for your standing corner swap combos, 6A>IAD j.A>j.D>dash j.B is by far the most stable, and will guarantee corner swap. The only problem I've found with it is that it doesn't work on Plat, no matter what alternative version of the combo I do. I really can't find anything stable for her. Didn't test on everyone, but it works on Carl, so knowing Plat's aerial hitbox, she's probably the only one that causes problems. Other than that, good stuff.