It might take a while to find the ideal setting because of the myriad adjustments. But for people with especially wide backs, the side bolsters, even at their widest setting, could feel constricting. I think the Sport seats are generally most comfortable for people with relatively slim builds. I'm only 150lbs so I find them supportive and comfortable.
2012 X3 35i | CB/Oyster | M Sport | Premium | Tech | CW I & II | DHP | Premium Audio | Apps
Past Bimmers: 2008 135i SGM, 2007 X3 3.0si SBM