For what it's worth..........
My o pin ion on the radial pin...........
The radial pin was designed for one thing .....and one thing only. To locate the shaft in the exact same position each time it is screwed on to the butt.
This was one of the problems with the 3/8-10 design. With the V style threads the shaft is trying to locate somewhere on the threads as it is being screwed together. Because of it's design, never in the same place though. Even cutting the threads in the shaft with a high speed cutter would still result in location problems for me. Every time I would tighten the shaft and butt together there would be a little offset that could be felt at the joint area.
This I believe was causing the faces of the joint to wear unevenly over a period of time and caused other problems.(crooked joint area when tightened down)
Kersenbrock and/or Franklin understood this sometime ago and along came the flat bottom thread design for poolcue use. With this style of pin you have a more defined area in the minor diameter of the pin size to locate the shaft on. If the hole in your shaft is bored or cut with a high speed cutter(not drilled, because you can not acheive an accurate hole by drilling and tapping it in wood) you can regulate the tightness (feel)that the shaft has when being tightened down.
One of the major reasons I wouldn't use a radial pin for myself is that you are confined to the use of "tap" to acheive the fit of the pin at a pre-determined hole size. Then depending on the circumstances, one may have to fiddle with the fit to either loosen or tighten it as the cue gets used and/or changes enviornment(sp).
If the cue is properly used for what it is intended to be used for and not as a weapon or a defense shield, the shafts in the BIG pin designs should out last most of us if the construction techniques are sound!
Just one more opinion in a world of many................