I've got 150K on my X3, I know its different but I have not had any trouble with my xdrive.
I see you're in TO, do you really need xdrive? I actually commute Barrie to Markham and I was considering just a 328i and putting winter tires on it. The X3 is my wife's, we have a small cottage up north, that's why the X3. The 328i would be my DD.
Life is like a sh!t sandwich...the more bread you've got, the less sh!t you have to eat.