I also really like the X3 now. A year and a half ago my wife showed up at my office in a new E70 for me to try. I didn't like it; felt to me like I had to get clearance from the harbor master before I could dock the "boat.". Took it back to dealer and got to enjoy his expression when I said I preferred the way the E53 felt. And we probably had that E70 out all afternoon.......
So good luck with this - I'm in the same situation. Bought this E53 for my kids to use, and while a couple of my girls occasionally still do, that particular purpose has passed. So I started using it pretty much as a daily driver for myself instead of my truck, and sure enough I ponder options (although i only hit 100k on the clock a short while ago), but i really just kinda like this X.