Can I suggest that you add the ability to see the gain setting in the graphical view of the compressor (this approach is demonstrated in many PC compressor plugins)
Basically The diagonal line rather than starting from 0,0 is shifted up by the gain value. (
This has the benefit of visually showing you the gain setting, and also being able to see if the maximum value can exceed 0dBFS on the output from the channel by where the top the graph intersects the top right corner.
Additionally I would ask that, just like the threshold and ratio, the gain can be adjusted by clicking in the graph and dragging up the lower section of the line, thereby pulling up the whole line in the graph, rather than having to move over to the gain knob to do this common task.