I'd say you'd hard pressed to find any better, in my experience the Barnes is an outstanding performer & the TTSX should be even better (i'm just starting to play with the TTSX myself). The 200grn has a decent BC (don't be suprised if it's turns out better than listed), you should be able to stretch'er out a ways with out having to worry about close range performance.
I thought about the same thing so I called Barnes and talked to them and the Guy I spoke with said he recommends the 168 gr that rule of thumb for barnes is go with a lighter bullet and I dont remember why. Call them and see if you get the same reply.
I wouldn't recommend the 200 in a WSM, that is a REALLY long bullet for a short mag, I am using the 168 TTSX in my Lazzeroni Patriot (essentially a WSM), they shoot great, don't compromise powder capacity (mag length) & I know they will perform.