RAM is the key to big maps. With the 16gb model, you should be ok; the 8GB one will probably run into trouble on the biggest maps in late gameplay. The GPU doesn't make a whole lot of difference in my experience; I'm using an old 680GTX and have no issues, so the dual gfx on the Surface Book are unlikely to see much impact. Processor-wise, it's hard to get the exact specs for the Book - without knowing cores and frequency it's impossible to guarantee that it'll be fine, but given the general specs on the 6th-gen i5's I'm be willing to bet money it'll be no problem.