ReaSurroundPan , what a great plugin for surround mixes. I love using it, especially with control sources such as knobs, faders and touchscreens.
That's not as easy as it sounds however.
The plugin changes the order of most parameters in the parameter list if the number of inputs changes and if the number of outputs change.
The number of outputs rarely changes in a 5.1 or 7.1.2/7.1.4 mix. That's fine if those parameters didn't get put last on the parameter list. Thus any changes in the number of input channels changes the position of anything past the first inputs parameters.
So here's an idea that wastes as few 'parameter slots' as we shall deem useful. Please discuss and post YOUR minimum number of output channels you're likely to use.
Request goalOne mapping in either Reaper(midi/osc) or CSI shall work for the most channels as are most often used. Lets call that X channels.
For my work this is up to 7.1.4, thus X is at least twelve for post production work. Other users may increase that default count.
The parameters for the outputs are placed first in the parameter list. The more flexible number of input channels is placed last. Thus mappings that reference more than one channel would always control the parameters they're meant to control, and not an output channel parameter by mistake.
Anything more than these default number of output channels would be added at the end of the parameter list, so that list is as static as possible for the most amount of users.