Originally Posted by
FBinNY
Cams is cams. Internal, external doesn't matter. They' re simply ramps used to pull out one end of the skewer.
Theoretically true, but cam sizes vary. In practice, the design of most external cam skewers (larger cams) results in less clamping force (for the same hand pressure when closing) and hence less secure retention. Sure, that can be overcome with more force, I suppose. But many users won't bother with that, or even know that they should do it.