I believe the E53 4.8is came with larger rotors (355mm?). One way to get some comfort that the Style 74 wheel will clear the E70 4.8i is to find out if any 4.8is owners have used this wheel. If these wheels clear the E53 4.8is rotors, I would think the E70 4.8i should be no problem. I agree there is no information to indicate the E70 4.8i with sport package has larger rotors than the non-sport.
2007 X5 4.8i (Performance Center Delivery, Feb 2007)
Monaco Blue/Tobacco/Bamboo, Sport w/ 20" wheels, Running Boards, Premium, Technology, Cold Weather, Heated Rear Seats, Premium Sound, Comfort Seats, Comfort Access, Sirius
2008 M5 SMG (Feb 2008)
Space Gray/Black, Comfort Access, Premium Sound, HUD, Heated Rear Seats, Heated Steering Wheel, Multi-Function Seats, Power rear sunshade, Ipod and USB Adapter, Sirius