I don't hate the idea of a SFX show at all, but I would argue that USH could really use something like the Monster Make-Up show at USF. It doesn't take up much space, significantly lower in cost to run than a stunt show, would provide much-needed live entertainment, and fill the void of a "studio" show. I think it's small enough where you can build that in the same plot as whatever new attraction they would build in Simpsons. We can have both a new ride and a small show! I think USH should consider the plot of land wisely and think outside the box here. They kinda had their chance to do something like this with F&F, but unfortunately they kinda fumbled that. That's what they should do, but I don't see USH putting a small show and another attraction there.
Again, I would not mind a pepper's ghost-heavy SFX show, especially since we lost Mystery Lodge, but if you're going to add a Ghostbusters ride....make it a full-blown ride. Besides, I think a SFX/Pepper's ghost show would be an ideal replacement for the Parisian Courtyard, but themed to Sing or something.
I didn't hate Minion Mayhem back when it was in 3D. Now without it....what's the point?