Fixed Blade Thumb Notch Orientation?
Per Rob @ Strider Knives:

"On the folders and smaller blades (read:DB-L, SA, DB, EB series) we place the thumb notch on the side opposite the primary edge, so that when held in an edge-up grip the notch rests more comfortably in the palm of your hand.

This practice eventually found its way to the Mod10 sized knifes.

On full size fixed blades we place the thumb notch on the same size as the primary edge, so when held in a blade down/edge in grip, the thumb can comfortably rest on it.

Placing the thumb on the notch is ones personal preference. It also serves as an index point when sheathed."

Per Mick Strider:

"Rob nailed it!

Its a question of angles of leverage against your hand. If we were to flip it on the larger knives, you couldn’t get any leverage when you worked the knife…..you would build a hot spot on your hand very quickly.

Though it IS comfortable….that little angle doesn’t really have anything to do with your thumb in reverse grip…not on purpose any way….when I design a knife I use my own hands as reference, and when I hold a knife in reverse grip I go edge in…..which puts the ramp on the far side of the knife…."

MT (top) MT MOD 10 (bottom)
(Photo by L.O. Little on BadlandsForums)