Andy,
Agree, definitely not directional or asymetric. I have also moved tyres left to right and reversed on the rims, but still only managed to get 55000 from the rears and possibly 5000 more from the front, if I take it easy. I also had an issue with too much negative camber on the rear. Took the X5 to BMW Brisbane to get a Beissbarth (alignment equipment made specifically for BMW) wheel alignment, and asked them to stand the rear wheels more upright, but still within the allowable tollerence. This stopped the tyres from wearing prematurely on the inside edge. Why did I go to the Brisbane dealer and not the local Gold Coast dealer I hear you ask? Well, the local dealer's Beissbarth wheel alignment equipment is unserviceable, and has been for a couple of years (and still is by the way). They send cars requiring alignment to the local Tyre Power dealer and charges $110 for a $59 alignment.
Will probably give the Yokohamas a go, as they get some good reviews from the American Tire Rack website. They are asymetric, but can still be reversed on the rim so long as you also move them to the opposite side.
Regards Colin.