This is what you mean? It's about 8 degrees tilt. No idea what the effect on the airflow on the inside of the fork would be, especially if you take the rotating wheel into account which might redirect the flow. I would be surprised if XMCS did some CFD on it, let alone if other brands did such a study specifically with a rotating wheel. The effect could be negative, neglectable or positve. Who knows...
To me It's not just the ridge itself that's problematic, it's what it indicates about the shape of the blade above it. I won't rewrite what I
already wrote. You can see Factor got this very wrong on the Hanzo and fixed it on the Hanzo Track and One. And yes, I do think that until relatively recently, a lot of designers were doing this wrong, but it's less negative on narrow forks
And it's way more than 8 degrees. It's tilted about as much as the head tube, almost like the fork was designed to stand perfectly vertical
The front on shot that requiem posted is also very suspicious to me, because it's looking at the bike from above and it looks like it's pretty much the perfect angle to line up with the angle of the upper part of the blade, considering how thin it looks in that picture. I'm confident that if you looked at it when the bike and the camera were perfectly horizontal, it would present a significantly larger frontal area, also indicating that, again, if you sliced it with a vertical plane, the cross section would look like a wing pointing upwards like it's trying to generate extra lift.