I think they will be very similar. The QE doesn’t seem that relevant as you will be imaging against a bright sky I suppose. Pixel size doesn’t seem important either when imaging such a nebulous thing. The larger well depth of the colour camera may give a slight advantage in pulling out a fine discrimination of brightness levels.
This sounds like a rather similar problem to the twilight imaging of the dark side of Venus, where the results are critically sensitive to altitude and sky darkness. Martin Lewis did a lot of work in quantifying the effect of noise in those observations. He gave a talk on it to a BAA meeting a few years back, which is in the YouTube archive.
