I recall a talk by Mike Fremer and Ken Kessler at Heathrow 10 years ago, and also a Roy Gregory article about phono stages saying we get to certain point, but even at that level other things are emphasised. Likewise Kessler said that a kettle drum hit by a muscular man when replayed is interesting as systems pick up on the force, or the weight, or indeed the resolution, but never all at once.
Out of interest Mike do you believe each arm therefore introduces/subtracts a greater/lesser degree of tone? I see your logic insofar as it the arm in which the cable moves that has the greatest movement in the turntable chain in which a signal moves, which may well explain a lot.
I unfortunately do not operate in your circles so to speak so cannot, in all fairness, comment on the strength of one machine to another.