Yes, it's not a new idea, but doing is correctly has been a challenge.
The concern with thin necks has been the strength issue. T6 aluminum is not a spring metal; the force exerted upon it is cumulative and it has been a concern that over time (and dueling) a thin neck will begin to bend with all the force it absorbs. This same principle is why an aluminum wheel will go out-of-round over time, whereas a steel wheel will not. The same characteristic of shock absorbtion is also why aluminum is great armor for tanks, but I digress.
The tendency of people to prefer heavy, thick blades only makes the situation worse, since dueling with heavy blades will put considerable stress on the thin neck compared to a light-weight blade. And aluminum doesn't bend well, it just tends to crack, so that would be a bad thing.
I really hope that anyone contemplating making a thin-neck adapter would consider using a stronger material, like steel, that can handle the lateral stress, or make the neck thick enough to take the impacts. A "movie accurate" thin neck made of aluminum would eventually fail if used (and dueled) with a 1" thick walled blade.
But then we have another problem because when aluminum is threaded with a ferrous metal, like steel, you get corrosion, so an aluminum MHS body plus a steel emitter would be a bad combo.
So yeah, this is what we sabersmiths have been struggling with and discussing with machinists. But I kinda figured Corbin would be the first to come up with something. He's good like that ;)