If they have this function, then it seems logical to me that they could easily introduce channel ganging. This could be done in the menus, but it seems like a quick shortcut could work also. Here's how I would do it:
Hold PFL for the channel that will be the master control of your ganged channels. (... and in the darkness, bind them.) Holding a certain number of seconds will pop up "channel gang mode" on screen and the PFL switch may then be released.
Press and release the PFL for each slave channel (ex.: Hold channel 1, press and release 2, 3, and 4 and now those four channels are controlled by the channel 1 gain pot.)
To un-slave channels, repeat the above steps toggling the slaved channels off.
Regarding the STOP + PFL shortcut, why couldn't they just use PLAY + PFL instead since hitting PLAY on its own while recording probably wouldn't do anything?