They're also all shaped almost exactly alike...that's sort of the point of B&M.
...if you were referring to the 2nd one, look at some pics, it is supposed to be odd shaped...
Not really. All B&M corkscrews are shaped pretty much identically to each other, with the exception of their size (and, in this case, the angle of their exit). The actual roll function is, as far as I know, identical on all of their wingovers, be it on an invert, floorless, standup, or sit-down. Hell, I'm guessing Manta's wingover is the same, too, but I've never been on it to confirm that one. Basically, B&M's corkscrews have a roll transition such that the rotation in degrees/second is constant throughout the element. Note that this is different from Arrow's degrees/meter constant. Since the train is travelling slower at the top than the bottom, the track must rotate faster (in degrees/meter) at the top than the bottom, hence the "B&M snap". let me know if that makes sense or not...I think I did a pretty good job of explaining it.