Definitely agree with Pyro here - foes are either susceptible, intermediate, or resistant (to use antimicrobial sensitivities) to the instant death in-game. That's just how it works, and by the time you get it, there are more resistant opponents, and spamming damage works better overall for clearing things out. The ID went about 40% off Extinction and 50% for Klarth's Chameleon when I tested it...I don't remember what Pyro's numbers were, but I think they were similar?
As Pyro said, there's a lot of status that honestly you may find worthless in-game that becomes better in the DL. It happens, and should be rewarded/punished equally (i.e., don't respect any status that wasn't useful in-game, or respect all of it...then this runs into in-game use arguments! yay!).
I can do a count of the total number of viable ID-vulnerable enemies later today, but it's more than 10% in the Future, and far more than 10% overall (for all the the Future is all that probably really counts). It's at least 50% or so, I'd guess, since there are foes both of the intermediate and susceptible variety.