I have to agree with you about the political bs. I am guilty for making one such post a couple of days ago.However I think that most of the talk is going on because of close proximity of the November Presidential elections. At any rate I think you should go with the 6mm Bench rest for the cal of the new rifle. I have a 6.5 Grendel and I love it. But like most calibers that are made to fit the .223 AR platform they do have their limitations. Lets face it they are like many tools, designed to perform a specific task.
I notice that you were talking about the Polish RSB on the Archer, I have successfully copied them for a couple of builds, Let me know if you are in need of one. I could probably get one fabbed up for your build.