Don't forget the arranger keyboard handles the "Left hand bass", "Drums", "Piano" and a "Color sound"..better than then any combination of straight workstations...Even my "old "G1000 works perfect in this situation...

If I can only have one keyboard ,it has to be an arranger,,,nothing else is so flexible..
Also concerning the use of an arranger in a band,there is no accidental surprizes if you set up a performance[Roland] or a registration[Yamaha]..for live play..you can turn off any possibilities of an accidental arrangement or drums, sounding...

You have all your mixing and volume controls right in front of you, and a quick selection of sounds at your finger tips, without disturbing your basic "band set up"...throw in the control features of an expression pedal[to control any selected part/sound], after touch and other controllers.....makes the arranger unbeatable..even without the auto stuff and SMF playback..