To me what makes this protools feature powerful is not only the speed (which is really important) but the fact that all this automation is pre fader (so before any dynamics processing) and is visually reflected in the waveform (so its easy to see your changes). The problem with Cubases current clip gain system is the fact that you cannot draw nodes. It works fine for adjusting the volume between phrases where there is silence (split the region and adjust the gain accordingly) but as soon as you try use it adjust the volume of a word or note in a phrase, you will hear a very audible and unnatural jump because there are no ramps / nodes to smooth out the change at the cuts. Adding node ability in clip gain would fix this issue and make it much more useable IMO.
I wonder if a quick solution would be to code it so the PreGain automation (in the PRE section of the mixer) to reflect changes in waveform gain visually? Would there be any potential negative to using pre gain this way?