I have owned a ms210, and have run a ms250 it depends what you are trying to do with it. MS210 good limmer and good for bucking 4-6" stuff. 250 will give you the power you need if you get to larger stuff 10-12" and still has the light weight for quick limming.
My .02
Good luck
210 and 250 are really identical except for the power. But the 211 is a newer, smoother, lighter design.