Owned a 3.0i X5 for 8 years. It was great. Lots of ways to make it look at sound more then the 3.0i. 4.8i wheels and fenders bolt up, 4.4i or 4.8i exhaust bolts up. Any of the goodies you want out of the "other" models bolt up.
The inline 6 was great. Towed a trailer back from the USA with my E30 M3 on it without any issues. Yeah, it's not a V8, but the thing pulled smoothly all the way back with some downshifts on the bridges and hills, but nothing dramatic. And long mileage trips got excellent gas mileage. Was running the OEM 4.4 5-spoke 19" wheels.
Now I drive a Mini Cooper S Clubman. I miss the X5 at times though. We put the X5 through hell with our family of four. And the piles of wood I use to carry with that thing............. was very non-BMW-owner-ish behaviour !!