It's only Kaleido that halves the resolution of colored content. The RM Pro is Gallery 3 and offers full-resolution color.
But a bigger difference is that Gallery 3 uses CMYW pigments; there's no black pigment, rather the microcapsules themselves are tinted black on one end, so the black ultimately ends up a little impure. Also there are only 4 shades of grey for antialiasing rather than 16.