[Golfie McG]

Golfie,

Not ducking the question but to answer it in full would merely diversify and prolong the argument; from which original we have already strayed afar.

Suffice it to say that the flail can, more than adequately, be powered without any hip or upper body rotation at all, be it by hitting or swinging.

Swinging: take a club in your left hand and, without rotating your hips or trunk, extend it as far back as you can. Now swing the assembly through the imaginary ball and see how much speed you have got and how you are compelled to allow the body to repond to the swinging arm in order for the motion to be completed. Listen for the "swoosh".

Repeat the process but with backswing torso rotation. Do you hear any difference in "swoosh" sound? No, I thought not, so what does that tell you?

Performing the same motions (Hitting) with your right arm only and your experience will be no different.

Burner,

Of course, in your example, I concede there to be very little difference.

However, the single arm example excludes (without massive strength) the structural possibilities that having two hands on the club bring to bear. If, for instance, the left arm were rigidly attached to the sholder, there would be a large difference in flailing action as there would be much more angular momentum (from the turning body) driving the flail.

Any questions?
Golfie