Ash, the FR I posted looks different because its a different CD, so ill leave that out for now. I'd post measurements of the DE250 / DNA-360 but I'm away for work and don't have a full set of polars anyways. So here goes based on what I've seen and measured.
The SEOS / DE250 combo does in fact have a board peak at 4khz as shown in the Bagby measurement posted here. It's not a problem because its consistent off axis. So if you eq it into place, its fine, it's eq'ed evenly. It would be bad if it diverged or converged off axis, like the Geddes on axis hole. But it doesn't. So the designers go ahead and eq it away. Myself, I use a parallel notch out in front of the high pass something like 0.5mH, 5uF, 10ohm. Can't recall the exact components. Other designers have other ways of doing it I'm sure.
The droop in the top octave is a little harder to explain. This is largely, IMO, a matter of calibration of test equipment and slight angled mic placement. That's the best answer I have. Could be CD variation too, I dunno. But the calibration and angles are the most sensitive in that range. Overall though I think if you looked at the reliable measurements you'd see this isn't that big of a discrepancy.
The low end hash in Bill and Brads measurements are strictly this, Brad's is wrong and Bills I'm not sure. That's actually the first I've seen Bills. I was involved in Brad's work and immediately warned him something was wrong. If you look at his thread, I also pointed out the identical issue in the woofer measurement. We all felt it was probably electrical, laptops are prone to this issue. The bottom end hash is just not true. Unfortunately Wayne has used these openly admitted suspect measurements to advance his product, and he knows better.
Now if we look at th