Clean can mean both. Some cameras can't output a video signal via HDMI without graphic and text overlays. Others can, but the signal is castrated, with reduced bandwidth, resolution etc.
As for why the Hyperdeck... I now have a Sony NEX FS100, which can output uncompressed 4:2:2. The IQ from the camera's AVCHD2 codec is very good indeed, but for some things (such as heavy grading) and greenscreen work the Hyperdeck allows for totally uncompressed output at 1,020 Mbps. This is vs the 24Mbps of AVCHD. The downside is that the data rate is horrendous... 10GB per minute.
I'll be writing this all up in a series of articles later this winter and spring.
10 GB per minute...pfff, that's where the burden is.
I'm also into the process of testing as soon as I can the hacked GH2 HDMI output with the NINJA also 4.2.2 and the file size is a dilema.
All the storage system has to be actualized to high-end standards and I'm doing the numbers and they raise at the speed of light because I don't see anything but a server solution. I asked "my" tech about the costs and it doesn't make me smile at all, but that's actually the cost of motion when done "the way it should".
Honestly, at those values, RED raw files are extremely friendly user and even if uncompressed 4.2.2 at those bitrate is going to be a solid footage for post, I hardly doubt it can compeat with 4K raw video that ocupates less space and will be much more flexible in post. (without talking about the hability to crop and downsizing from 4K to 1080)
But it would allow anyway those incredibly good minicams to be usable in high-end imagery in post.
But Red 's got it IMO.
Cooter was right when he was saying that there are false economies. (and the same dilema will be true with the D4 etc...)