The X5 most likely won't get the 3.0 turbo until a facelift.

Yup, for me that's the sweet spot for when to buy a bimmer. The 3rd or 4th year facelift usually has some additional features, more power, price is more negotiable, and bugs are mostly worked out. I've got myself on a nice 6-7 year cycle for bimmers, falling right in the 3rd or 4th year of a model's production. There's some reports of the I6 turbo running hot in the 335i, all the more reason to wait a bit for the bugs to get worked out.