So besides the obvious differences in magnification range and objectives, is there a significant difference in the glass quality?

I have a VX-R in 1.25-4X on my .416 Rigby and it has held steady over 100 shots. I'd give consideration to the 1-6X in the VX-6, but that's a big jump in price.

Eye relief is constant in the VX-6

Field of view is gigantic in the VX 6 compared to the VXR and other scopes.

I was just going to start a post on this subject. Leupold states that the VX6 1x6 has a FOV of 223 feet at 100 yards at 1x. Is that possible and do you want that much FOV? I don't like seeing my barrel in the scope but with that much FOV I think you might see your hand on the forend. I have the Euro 1.25x4 on my 376 Steyr with 23" barrel and I can see the barrel in the scope when the scope is set at 3 power or less.