Purely anecdotal here, but when I see WN gatehouses, there's the regular cluster of people, but they're all lined up. They know exactly where to be in line, and proceed. Boarding an airplane, especially a narrowbody, is going to take a while. However, I don't seem to see as many carryon luggage (as opposed to a bag, purse, laptop case, etc), except maybe the business traveler or the kid visiting his parents for the weekend. From what I hear from most leisure flyers that like WN, they check bags and brag about no checked bag fees, and unless they're in a hurry to get off the plane and go, they probably will check luggage.

However, to get on a tangent, as orderly as WN's boarding process seems, there are still hangups. They're all in line, spaced out due to the several-seconds delay to scan a boarding pass, but then they all get jammed up again as people try to decide which seat they want, scoot past others, put bags in the overhead (and block the aisle). I guess the only reason I bring that up is because of the constant debate of "if they got rid of bag fees, people would check more bags, there'd be less congestion in the aisles, and people would get their coveted bin space." It seems like the airlines have different pieces of the puzzle, but no one has been able to put them together yet.