One of the best features and very useful for me in an arranger is the harmony effects which is not possible in a synth or maybe in workstation. I can play lead with harmony using only one finger. Of course you have to turn off the drums o9r beat. all you have to use is the chords in which the harmony rely on. As far as choosing patches or voices in live situation, there are some synths that already has buttons of different category in which you can assigned what ever sound you want. The Roland XP's like XP30, 80, 60 have those thing. I agree that arranger keyboard s have some very important and useful features for some musician. I wish there were a mini arranger (37/49 keys, slim with no speaker or maybe a small speker)keyboard with full features out there. anybody knows one?