I hadnt considered tube length for mounting but figured there is an easy solution for that, even if it means mounting a rail. As to eye relief, the VXR beats the VX6 by 1/2in. Field of view , the 1 power obviously will have more but I guess that leads me back to my original question: Has anyone ever found the FOV at 2x lacking so much that hey couldn't make the shot where having a 1x would have made a difference?
I have Leupold VX6HD 1-6 and VX6HS 2-12 scopes.
For me, the true one power of the first far outweighs the extra factor of 2 magnification of the second.
Looking through the 1X setting of the 1-6, the view seen through the scope transitions without interruption to the view outside the scope, if you shoot with both eyes open, giving true binocular vision, as with eyes only. Not so for 2X (or 1.25 X, 1.5x, 1.7X). The advantage of the continuous field of view is huge, in speed of target acquisition and tracking capability on moving game.
For the 1X, the field of view is twice that of the 2X, a benefit certainly, but I don't see it as a make-break factor in the comparison. FOV of the 2X is adequate for close work. But the scope FOV-reality FOV transition leaves a big blind spot for the 2X, a discontinuous total FOV.
A max 6 or 8 power upper magnification is good for 400 yds no problem. The 6 power brings a 400 yd target to 67 yds; the 8 power brings a 400 yd target to 50 yds. Unless shooting bumblebees, this seems adequate to me. Of course you may be a bit more comfortable with greater magnification, but probably don't really need it. For longer ranges, the picture of course changes.
I've wanted a true 1X scope for 60 years. The great sighting advantage of the scope isn't its magnification but its no-alignment sight picture - just place the cross hair and pull the trigger, no messing around with old-school iron sight alignment. I think this is 60% of the advantage of a scope. Another 30% of its advantage is in giving a clearer sight picture under low-light conditions. These are a big deal to older shooters. A little magnification is nice, but is a secondary benefit to the scope sight.
Unless you'll never have to quickly acquire a sight picture in your shooting, especially on running game, strongly, strongly consider the true 1X bottom power scopes. LeupoldVX6 1-6, Swarovski Z8i 1-8 are excellent sights that I've used. Expensive - yes. The best available - in my opinion, yes, hands down. The Swarovski Z8i especially offers an ideal magnification range, and its circle-dot illuminated reticle is very very good. Other makers probably have as good products, I'm just not familiar with them.
Get your hands on a true 1x and test what I mention about the FOV continuity. Don't buy a scope without looking at this. Unless the true 1X is price-prohibited, which can easily be the case. Then the 1.25-4 is pretty good.