Use Atom or similar to trigger items in Arranger view for performance and testing out new arrangements and have Arrangement Layers function..
'Arranger Layers' are where these new arrangements are temporarily recorded and you could have the option to make this new arrangement the definitive one. Also you could have the option to edit this further using options available for Automation, so you could literally punch in variations to an existing arrangement on the fly. Several Arrangement layers could be present with option to collapse them just like you do in normal layer use and even an Arranger comping function could be brought in to combine the best bit of different arrangements..