Re: 300WSM twist rate
There is not alot of difference between the 11x and the 10x with 150-200 class bullets. In other words the 10x is not going to hinder your performance over the 11x with those bullets. That said, a 10x will handle the heavies a bit better. 11x is really the minimum needed for the 208 or 210's but IMHO, the 10x is a bit better suited for the 210 class bullets than the 11x even though the 11x will work. If you ever want to shoot some of the mono metal bullets up near the heavy side, or bullets heavier than the 210's, the 10x will handle these MUCH better than the 11x.
The 10x gets my vote as well.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.