Anybody tried one of these. Tried a search and didn't get anything. Just wondering how they compare to the armalite mount.

Also how does a mount like this compare to mounting rings directly to a flattop.

I have used a Wilson Lo-mount with a Leupold 3-9 compact scope for the past several years on my truck gun that gets beat around a lot.  It is very sturdy and has not lost zero.  You may find it difficult to mount scopes with long eye relief far enough foward for a comfortable cheek weld using this mount.   A friend liked my set-up and combined the same mount with a long eye relief scope...he wound up putting a spacer on the buttstock to move is head position back relative to the scope.  I have some sturdy rings on my .308 flat top that also work great.  No eye relief problems here because of the larger real estate on top of the .308.