I think I have a sense of what Raul is talking about. He has mentioned that he has or is familiar with and likes a Kuzma 4P. I have one of these on a restored and modified Luxman PD444, mounted together with two vintage SME 3012R 12" arms. This SME has the heavier stainless steel wand that improves significantly on performance and versatility with MC cartridges compared to aluminum wanded 3012s. Within the SME hierarchy I much prefer the 3012R over an SME IV.
This three-armed PD444 has had a rotation of MM/MI and MC cartridges of widely varying compliance, to the point that each tonearm has revealed a few personality traits that are independent of cartridge compliance. Except for these consistent traits, I don’t hear much difference between these arms across a wide range of cartridge compliances.
The Kuzma is absolutely free of HF noise artifacts. Its spooky calmness suggests either a slight HF roll-off, or if not roll-off, then damping at a threshold that might be confused by "uneducated" ears as a roll-off or loss of air or extension. As I have the same reaction to very low-noise SS electronics like my Pass XP-25 phono stage or XA-160.8 monoblocks, I’m coming around to the idea that my ears have been reeducated to listen for what’s missing(distortions) as much as what’s included(music). I don’t much miss an all-tube system.
I suspect that one reason the 4P is so good with both low- and medium-compliance cartridges is its exceptionally smooth but tight bearings. I don’t think it’s really possible to separate the contribution of tonearm effective mass from the variable of bearing friction(which presents resistance to inertial mass), or to consider resonance independent of bearing design. Point bearings may be particularly good in dissipating vibration into heat in ways that balls in races are not, and in an arm with point bearings, four points may be better than one. It may even be true that approaching SOTA in a modern tonearm, a relatively frictionless bearing could force us to rethink the inertial mass problem.
I’m inclined to consider the 3012R as more neutral than the 4P, partly by virtue of its particularly open and alive sound-- similar to what Raul alludes to as favorable to Japanese audiophiles of the vintage era. If these be distortions, then at this level of performance I’m willing to accept even subtle distortions into the realm of taste.