I have never bought them, the gun either came with every thing Or the shop put it all together for me. So I really have no Idea what I am looking at as far as what will fit and what wont.
And yes the Vortex stuff is really nice. I have the same scope on my 308, it just has a different reticule is all. I am really not sure which rifle will end up with which scope but I have been very happy with the one I have so I figure I might as well try another before people start buying them up and running up the price.
I had one scope (a Leupold) on low bases that was fine UNTIL I decided to add a set of Butler Creek flip-open protectors. That little bit of extra thickness on the Eyepiece was all it took to make it to where I could no longer open the bolt. I had to go to medium rings to get the needed clearance.
Bottom line is that sometimes a gnat's hair can make the difference between using a low, medium, or even high rings.