Or have two similar amps set up a dual amps and then switch one on and the other off using a footswitch. Will get you to the Not Enough DSP prompts very quickly though.
There are suggestions on IdeaScale about being able to save and recall "sub-scenes" which if you think of a scene as being a combination of Amps and Effects, then a sub-scene is the set of settings for all the controls.... so switches would without having to reload the patch be able to change nut just amp settings, but all of the effects.
L6 would point out that the way to do this might be simply save a copy of the patch with tweaked Drive setting and switch to that, but you would loose Reverb and Delay trails and any effect setting changes made.
There is one more option which I know is a bit radical in the digital age..... turn the guitar volume down for less gain and turn it up for more. Sometimes the simple old fashioned method is the best!