The metric that needs to be discussed here is the lesser of the two evils which makes us wander into the land where ears become the ultimate arbiter. At that point individuals are allowed to have differing opinions and the vast majority here are respectful of others who have taken parallel paths.
Any offset is picked up by the cartridge as noise or coloration depending on the motion involved.
I see two possible situations here. Lets assume a 3° Zenith error at a given point on record. In the case of a traditional tonearm rigidly fixed in all but the lateral and vertical planes, the misalignment will cause a force in a direction that the tonearm is prevented from moving so it will need to be transferred to a direction that movement is possible which will come at some sonic penalty. Now consider the same situation with a tonearm that allows 'some' movement in a third direction. I'll agree that this will also add some sonic penalty as you describe but also see the possibility that it could be a much more benign penalty than in the first situation. Now take this a bit further to the extreme of a severely misaligned cartridge and we have the discussion at hand. The idea of mistracking reminds me of the mike tyson quote “Everyone has a plan until they get punched in the mouth.” Thinking you are going to have a setup that won't mistrack is akin to planning on getting into the ring and not getting hit.
I suspect the longer arm, like any other longer arm, suffers the issue of greater mass. You may well need a cartridge of lower compliance.
Oh boy.... there is another can of worms in audio that needs to be re-examined. I presume you are referring to the tonearm resonance. Everyone here should go ahead and add weight to the headshell to double the effective mass of their tonearm and see if their resonant frequency changes by the predicted factor of 1.4.
Do You think that an observer with good equilibrium objective/subjective can in any way trust on that even after " thousands of observations?, makes no sense at least to me.
Can you give me one "objective fact" in audio that is not firmly based on a solid foundation of subjective experiences?
dave