@mwatsme - yes, I agree that a narrow baffle helps make the speakers disappear by reducing the front baffle reflections. I think the wave guide used by the X4 does reduce the affect, but probably doesn't eliminate it altogether. I listened to a few songs on them at Pacific Audio Fest and thought they had a nice sound stage, but I wasn't that familiar with the songs that were played.
One of the things I like about GR-Research's designs is that they use a folded baffle design so that the front baffle is as narrow as possible while still providing more separation between the driver front and back wave, lowering the frequency at which cancellation starts to occur. Like the Linkwitz speakers, they do a nice job completely disappearing
On the other hand, I do find the Spatial Audio speakers somewhat more attractive. They have a nice clean look.
I've heard some very nice box speakers, but they were also VERY expensive. As a percentage of production cost, a lot more of the expense goes toward the cabinet in high quality box speakers. An open-baffle speaker with comparable quality drivers and crossovers can be made for a lot less.