Ebb Try this:
87:01:1a:28:02:00:c2:33:c4:86:4c:1d:b8:0b:d0:84:8
0:3e:13:3d:42:40:e8:03:32:00:10:27:90:01
Make it one string obviously, I've taken the string from the Windows GUI, instead of the app.
Holy crap, yup that did it -- wow this looks great! HDR Game with DC off now looks about the same as Cinema Home with DC on low; switching back and forth between the two I can't really tell much of a difference. Like you said, I can notice a tiny bit of clipping, for example when I look up at the sun/clouds in Horizon, but its well worth the trade off for the extra brightness/shadow detail IMO, and nowhere near as bad as Standard/Vivid.
Also - I'm now able to toggle the metadata injection on and off via the app without restarting the device. I think the theories about HDR Game mode assuming 4000 nits peak brightness are correct -- toggling the metadata injection seems to do virtually nothing in any of the other modes aside from Game mode.
I don't want to oversell it - it's still a pretty expensive solution to an issue only some people have a problem with, but it essentially gives your B/C7 the Cinema Home tone mapping like-settings at the 21ms latency of game mode. I'm pretty happy with it, and while the device cost me ~$160 (on sale), its a whole lot cheaper than upgrading to a B/C8.
Thanks again DOTDASHDOT for the recommendation. I'm going to play around with it more tonight when it gets darker, and can post some more impressions then