Difference between Z4 Sport Seats and M-Sport Seats

Hey guys, I live over on the E90 Forum. I'm looking at a Z4 3.0si Coupe as a daily driver. I'm going to retire my 270K E90 from DD duties. I've got two Z4 Coupes in mind, one with sport seats and one with M-sport seats. I'm a bit of a hefty dude and fit snugly in the sport seats in my E90. How tight fitting are the M-sports seats compared to the regular sport seats? I'd like to get an idea before I go test-fit the M seats. Both cars are a few hours away from my office, so I don't want to waste time if the M seats are that much tighter than the regular sport seats. I searched to see if this question has been asked before and didn't see any related info. Any help would be appreciated.



Thanks in advance.