Mesa Tactical is your best bet. I can CONFIRM that the stock rail can bugger up mounts... my Larue T1 low mount was somewhat 'deformed' on the bottom by the stock rail. It still works, but it's not pretty.
The Mesa rail/side saddle setup works really well. There have been reports of the receiver holes getting 'deformed' when under heavy use while the sidesaddle is loaded with shells, but it's usually empty when I'm using the gun. Apparently the weight of the shells, combined with the relatively 'soft' aluminum of the receiver can cause elongation/stripping of the holes.