Digital rear–view mirror with side cameras(Cameras next to the mirror not below it)

[AlphaDad1906]

I understand that there is an option for additional side camera's on the 2500&3500s. Anyone have them to enlighten me what additionally gained in addition to the surround view? I've seen the basic surround cameras turn on with signal light as well as show up in the digital rear view if equipped. Is it just a clearer straight line down the side?