Lee, I thought he said he had calculated it. The chart is in Post #1115 here:
http://www.cloudynights.com/topic/53...a-test/page-45
and on page 47, Post #1159, he explains it all - not that I understand the math.
Honestly the QE is so much better than my DSLR that I won't split hairs on the absolute value. I don't know that the intention was to kill off 674's market.
As to Jon Rista work, I won't call him ' The Oracle' but he is doing some good work on this topic. He has now revised his 'Sweet Spot' recommendation, quoted here in a new post:
"There is definitely more testing needed to find the sweet spot for this camera. My original guess of a gain setting of 60 was close, but not dead on to maximize DR and minimize noise. I tested a gain of 70 last night, with bias offset of 12, and that seems to be closer but still not right on the ball. "
I will try 70 and 12 tonight on various sub lengths, and targets.
And thanks to Jerome for reprocessing my M8 image to demonstrate that the core is not blown out - it was just my hacker processing that caused it.