Originally Posted by
LesterOfPuppets
It only matters if you have horizontal dropouts. The external cams often won't clamp well enough to hold a rear wheel in place on horiz dropout.
This is not my experience. I have had creaking issues with external-cam skewers that were very difficult to track down and only went away when I returned to internal-cam skewers. I might be unique in this regard but I kind of doubt it because I'm very easy on equipment.