koivu,
First things first,here. Just how big of a deer are ya talking about? Some of the northern deer get pretty big. Down south,where I'm from,a 200 pound deer is a whopper! If you live and hunt up in the big deer states, you might want to rethink the 6mm. Also let me say this,I own a 243 and woldn't get rid of it for nothing. There are a lot of rifles out there that are small in stature but can pack a punch also. The other thing about the 6mm REM is ammo availabilty.Check closely on this because unlike 243 Win, You generally can't find this ammo at your local Wallyworld. Just some thoughts to some of your questions.
HWD