I use the Grand Aero mirrors on my X5 as well. They stay very secure and accommodate the curved mirror housing with its two clamp format. Be sure to check the clearance between the edge of your factory mirror and the inside face of the housing. That gap is where the clamp feet sit and the clamps feet can interfere with your factory mirror movement if you're not careful. The mirrors have a very, very slight vibration when on the highway, but that is because they are fully extended. Even with the slight vibration, I would recommend these mirrors.
'09 BMW X5 xDrive35D (TV)
'05 Porsche Cayenne (Wife's)
'15 Flagstaff Micro Lite 23LB (TT)