I'm late to this conversation (I thought I'd already posted) . . .
Yes, I feed live feeders to my "mini-monsters" (hogchokers- a bottom dwelling ambush predator: "flounder" [actually a sole]).
However, the 'live feeders' live with them and they snack off the fry (I think, I've only actually seen one fry eaten, but I have very few molly fry). The "live feeders" are mollies and ghost shrimp. I also feed the hog chokers earthworms and hikari carnivore sinking pellets.
I will admit, seeing a predator strike at prey is part of the excitement of owning some fish. I do feel bad about the prey sometimes, but usually my predators eat the food rather quickly (inhale it) so I don't think the prey suffers too long.
I feed live food to my mudskippers too, but that's crickets and earthworms (along with other prepared foods).