and I have a much harder time with thumbers, in order to get that last 75' out of them I have to turn my forearm a slightly different way. This is my theory du jour as to why people are better with one than another.
Throwing overhand is not an easy thing for a human arm/shoulder to do. Most of us as kids learn to throw balls and spend hundreds of hours throwing footballs, baseballs, rocks etc.. to develop that muscle skill. One of the things we learn is how to pronate our elbows in conjunction with our shoulders. My theory is one of these methods of throwing overhand (Thumber or Tommy) will feel more natural to our learned elbow motion.
But if we really work on it, we can get our overhands to take reverse paths. I am getting pretty good at using a Spirit to go right late on a tommy, so I'm torn as to whether it is worth it to force both shots. And as you explained, you already have a nice alternative. If you have to learn one, the Thumber is more useful IMHO.
btw, skamahawk is what exactly? I see the potential for knife hyzers replacing this shot, but the fade/bounce/skip aspect of a knife hyzer still is a long way from mastery for me.