wk154, based on your description, which is the need for a simple pair channel grouping, it would make sense that mackie could enhance the channel linking function to allow you to link "fader only" vs "stereo".
Visually it could do what I do on manual boards -- put a piece of console tape across both faders to lock them together for one-finger operation.
On the iPad it would appear similarly, as two channels, but with a fat fader knob spanning both channels or a bar connecting the two faders.
Would you go for that?