Actually, I think Jobst is saying the elbow in is less likely to cause clearance issues with rear der. . . . under load, the tightening, inter-laced, cross will be pulled IN if the elbow of the pulling spoke is IN. . . . but I'm not sure if there's a statement of quality or correctness there, just one of the physics of the situation. . . .
I don't think the elbow itself is at issue since it is always covered by the cogs, but rather the crossing, which is generally just outside the radius of the cogs, and therefor potentially near the derailleur. Brandt and Brown both indicate that a build with pull spokes elbows in causes the spokes to move away from the derailleur under load. I was taking that as advocating a particular build style, and that that was the style that Mike Garcia used to build the "Mongrels"