"Perplexing for sure, as I don't doubt the transfer used by MoC matches the color scheme of the film upon release."
I have serious doubts that the MOC color scheme matches the release print. The MOC disc looks blue to the core, and I have never seen a Johnnie To movie that was supposed to look that way. Even a picture like The Longest Nite, which looked rather blue in most scenes of the DVD, appears to have a more subtle, life-like, and broader color scheme in the theater. The only disc of a Johnnie To movie that matches MOC's blu-ray for blue color-timing is Media Asia's disc of Breaking News. That film appears to be way too blue. I haven't seen it in a theater, but I doubt the accuracy of that look in the transfer. More than that, having seen The Mission, The Longest Nite, Exiled, and the two Election films in theaters, I have to say that none of them looked overwhelmingly blue. Certainly when the films hit SD-DVD they pick up more of a blue tinge in many scenes - probably a result of compressing a bit of subtle blue color-timing. But there is no way that Mad Detective should look so washed-blue as it does on the MOC disc.
To reiterate a little of what I posted on the MOC Mad Detective thread, telling signs to me are the flat compression of the forest scene and the nauseating green-blue clash shown in the capture with Lam Ka-Tung staring at us from said forest. Also the neon light in the convenience store behind Lau Ching-Wan - on the Mei Ah it is green, but it is completely blue on the MOC disc. Light like that does not naturally appear blue for the cameras. Scenes like the one with Andy On in the breezeway take place in the middle of the day. On the Mei Ah the indirect light is yellow, looking like mid-day. On the MOC the light is-surprise!-blue. It looks like dusk.
The Mei Ah sd-dvd has a much wider color-palette than the MOC blu-ray. Certain scenes have blu-tinted color-correction, but nothing so extreme as the MOC disc has. I should say, I'm not actually trying to crusade against the MOC disc, but the Mei Ah, for all the grain, has what seems to me a truer and more expansive color palette. That said, obvious problems with the Mei Ah in terms of contrast boosting additive grain and cropping really suck. I guess my main point is that this doesn't jibe with the theatrical exhibitions of To movies that I have seen. The colors are always carefully chosen, but one never feels that the palette is being overtly stylized for such unconventional effects. The MOC disc makes it look like a Joel Schumacher film.