the velocity of the 200 may overide the effects of the cross winds about the same as the slower but heavier 300 grain bullet.
Sabotloader - the Hornady ballistics calculator confirms your recollection; very little wind drift difference between them.
but, i can not imagine shooting a deer @ 200 with a ML -it would have to be an out of this world trophy buck for me to even consider it....
Would you attempt a "peeper" out thar? (forget about the bullet choice)
Wolfhound - I cut my teeth with slug guns and admit to being a little hung up on heavy bullets. I've seen Whitetails carry hits from shotgun slugs I never would have dreamed they could handle. I'm afraid there is a tendancy to overestimate what a heavy bullet can do.