5D Mark III firmware with clean HDMI is ready right now.

[ROCKMORE]

Magic Lantern raw is 14bits of data from practically straight off of the sensor (almost), you can easily pull a Prores444 proxy from it for instance. No guesswork at all. Simply tons more data. The crappy 8bit output from the HDMI or internal IPB/All-I is pulled from far down the in-camera processing chain, this is why they are virtually identical.

Is it possible to record ML raw to an external recorder via HDMI?

 

[Celluloid Dream]

Is it possible to record ML raw to an external recorder via HDMI?

No, it is not possible and it never will be. ML raw is grabbed from a buffer memory area before the internal codec and HDMI processing chain. It was investigated and found to be an impossibility.