IceFalcon isn't a reseller for the GDFB stuff, he has his own styles made, so I'd take his word on it.
They don't look any wider at the triangle vs rectangular part of the "tube", but really, up or down, if they fit comfortably, wear them like that. The most important part on the chausses is orientation of the rings for expansion/contraction, so switching up for down doesn't matter much - upside-down and inside-out leaves the rings exactly the same way. I'm surprised there's no "belt loop" on them - mine had it, and I took it out. It was on the rectangular end on mine.
Kinda clueless.