I've said a few times that I have lots of Ute friends, mostly through church and work.  My observation is the basketball fans trend towards the more affluent LDS set, football is more of a hodgepodge of the population of Utah.  I've been to a number of basketball games at the U without issue if not downright hospitable, and have even gone with friends to non BYU games.  Pretty bland and boring group to be honest.  I haven't been to a game there in 3 or 4 years I'll admit.  This is just to say I think the basketball fans are closer to awkward dorks than trashy jerks.

I will say this for at least the past 10-15 years, the atmosphere at the Marriott is a lot more energized and fun than at the U.  Graet music, great events at half and intermission, they know how to put on a good show here.  At the U I've seen them trot out Jr Jazz teams to play for 10 minutes for halftime entertainment.  It's cute for about 2 minutes.