Actually I'd have to disagree with you Bob.
The value of this test is specifically that it is a side by side comparison in an uncontrolled environment. Granted replication of the test becomes impossible but for a comparison it's pretty nice.
By using 20g each in the same size tubes he's showing that the 95/5 down from the french source and thru-hiker have the same fill power in real world situations. However thru-hiker's down compresses better and has a more homogenous density (uniformly sized air pockets).
The french source claims the fp of their down is between 750 and 820...if we assume that's using the EU standards which roughly translate to 100fp ratings lower than the US standards we get 850-920fp in the US. So thru-hiker's down is at least equivalent to 850+ in real world environments.
This kind of reinforces why WM still claims only 850 although many say their down often tests higher. Thru-hiker obviously has a quality source for their down, however the rating may still be optimistic for real world use, however it still is a high fp none-the-less.
From WM directly:
"Fill Power Testing
To perform a certified test, a sample of down is sent to an independent laboratory. There the sample is placed in a large screened box and allowed to condition for 5 days before being tested. During this time the sample is stirred, mixed, and blown with a warm hair dryer. This conditioning is intended to stabilize the sample so that consistent results may be obtained. Then a 1 ounce sample is drawn and placed into a measuring cylinder. A piston weighted to 68.4 grams is placed on top of the down and when it comes to rest the volume of the down is measured in cubic inches. In spite of 5 days of conditioning, the laboratory will publish their results with a plus or minus 5% error. This is a full 10% range and for an 850 fill test, results in an 80 point variance! Furthermore, conditioning actually improves the sample by drying and blowing out dust and other small particles while the down at the factory remains unconditioned! This is what we mean by an Optimistic fill power rather than a Practical fill power rating."