Honestly, I'm not particularly disappointed in the proportions. Just look at the neck of an Obi-Wan and Jedi Luke FX. I assumed going in that there was no way the emitters would be as small as the real deal and fit a blade, at least not in any licensed product like this. The big thing for me is that the greeblies and details are so different from what we've seen before. Like the bits around the pommel definitely aren't what the celebration model. Admittedly, that one looked like a sort of rough casting, so maybe some details didn't come through, but the pieces inside the gash on the top are totally different. Both rubies and the Force FX have a sort of grille on the right, but display one had the vent looking thing on the left and a sort of double piston on the right... I don't really know what to make of that.
On a more positive note, I'm glad they have the right sounds and separate blade ignition. Make me hope there's a good Kylo soundboard I can pull out of the Hasbro electronic lightsaber for a relatively cheap custom.