Problem is we've seen it time and again with Merlin's attempts of theming/experience attractions, and I speak as someone who likes Sub Terra... There's always that ONE mis-step made that stops them from being that high quality they do strive to be... I've still not bothered with DBGT, but that it itself has been high evidence of the difference between theory and practical in terms of experience attractions...
Given rides a story for the sake of having a story does not work, bigger parks than Merlin have buggered that one up enough times... And tbh I don't think being to the level of Baron 1898's pre-show is actually that far beyond MMM; given that it is just well designed projection mapping, but the devil is in the details... Would Merlin add a little hatch that opens up when the ghosts appear, or have the physical scenery move when they fly off? As I say there's always that one step they miss that prevents them from going from good to great...