I have the D750 and the 24-120mm lens; both US. I also have a D810 and a backpack full of other lenses. I have Nikon power grips on both cameras too. I hate carrying spare batteries!
While I prefer the D810 for serious work, the D750 is lightning fast, by comparison. The much smaller file sizes of the 24mp sensor really do make a difference, in terms of write speeds. That said, it's rather small buffer doesn't take long to fill.
There is no perfect camera, but if you can live with the D750's small buffer, and add on the 24-120mm lens, which is my favorite walk-around lens, it's FAST (with fast memory cards), it balances perfectly, and you'll have a setup that's hard to beat at ANY price!