Just did some throws with Invictus, Warhorse, and Adder. I see a lot of similarity in how Invictus and Warhorse perform for me, ymmv. Different discs to be sure, but the function for me is the same--a wind-stable FH/BH distance disc. I throw it when it's strong HW or need a reliable anny flex that is sure to unwind at max power even with wind, and max safe distance.
Adder and Warhorse I got a chance to get some near identical releases. Both discs can absorb a ton of energy. On a low max-mph BH into a 10mph HW, both penetrated about 275' before going into the fade part of flight, and after contact both skipped twice, ending up about 325 to 350', within about 4' of each other. On a tailwind FH, Warhorse seemed to 'slice' the air a bit more, hard to describe it exactly. Warhorse went about 5' longer (about 330').
I think Adder is very comparable to the Warhorse, enough to invest in one. I think Warhorse might be the longer disc for the big arms, just a gut feel. But I can't throw that hard, so... For me, they are twins.