The Mutech RM Kanda Hyabusa

Mijostyn, Your indictment of the Trans-Fi tonearm would seem to be an indictment also of nearly every linear tracking tonearm, since they all have very high horizontal effective mass as compared to their vertical effective mass.  And yet there are thousands of happy audiophiles who use linear trackers.  (Okay, maybe only hundreds.)  Your critique raises the question of what is the comparative importance of horizontal vs vertical resonance in reproducing the full audio spectrum.  Since bass frequencies are primarily encoded in horizontal or lateral motion of the stylus, and since treble is primarily encoded in vertical displacement, I would think the question of resonance is very different for the two directions.  One guru mentioned that high effective mass in the horizontal direction is good for bass reproduction, because it inherently damps the overhang in stylus motion (the tendency for the stylus tip to keep moving due to its own inertia) once a bass tone has been transduced.  (I realize there is a guru for every opinion in audio.) Also, as you know, the formula we all commonly use to calculate tonearm resonance uses vertical compliance and vertical effective mass.  It's also difficult even to get the data for any given cartridge relevant to horizontal compliance.  So, I would say the situation is much muddier than you make it out to be, and furthermore that the demonstrable excellence of the Trans-Fi and some other top notch linear trackers, across the audio frequency band, should make us think twice about whether we understand the physics.

All that is true lewm but you have to add in record irregularities which are at very low frequency. If you watch one of these arms carefully you can see the cantilever move sideways back and forth except with perhaps the stiffest cartridges. This produces FM distortion. I was hot to try the Clearaudio TT 5 at one time until I saw one and watched the cantilever drift back and forth. Some are going to blame this on the bearing but I also watched an Airline do exactly the same thing and these records where reasonably well centered. I am not the only one who thinks this is a problem. I do believe keeping the resonance frequency low produces more accurate bass but with horizontal trackers it is too low. This is what makes arms like the Reed 5T and the Schroder LT so exciting. They are also lighter arms which have mechanisms for adjusting effective mass. 
I never use the equation now RF = 159 divided by the square root of mass X compliance. The figures are always too far off the measured values. I just stick to lighter arms now and add mass when needed. Arms with less inertia produce less tracking distortion given equal resonance frequencies.

I set up my tonearms with both vertical and lateral resonance tracks. With the arm I have now the lateral resonance is 1-2 Hz lower than the vertical so I compromise between the two. 

I have always found tangential trackers intriguing but on this one I am inclined to agree with Michael Fremer. Excepting the Reed and Schroder you are better off with a short, light and stiff pivotal arm. 

Michael Fremer is a perspicacious listener and good reporter, but on technical terms, he is often weak.  In the case where he criticized at least one linear tracker for high lateral effective mass, I believe he was parroting some other guru.  You can find "experts" on both sides of that question, and I am not saying I know better than any of them, but merely that the proof has to be in the pudding, for linear trackers one by one.  Sure, the Reed and the Schroeder are intriguing in terms of addressing that one issue, but they have other possible issues related to bearing friction etc.  I agree with you about inserting parameters into the equation for resonant frequency; we are usually kidding ourselves that we know the values of M and C with any degree of accuracy, for that tonearm and that cartridge we are using at that moment.

Let me preface by saying that the Terminator replaced a SME V and it was not even close. Now the SME V is not a Schroeder, but for the Terminator to outperform a veteran arm is, to me, impressive. And I also plead guilty to not appreciating many of the finer technical points in question. But the observation of lateral swaying of a linear tracker was one of the issues that concerned me when I started with the Terminator. As I have posted on my Terminator forum, recent experimentations on surge and soothing tanks have yielded tremendous sonic benefits. One of the physical manifestation of increased air flow regulation is...... almost no swaying. I observe perhaps less than 1mm right to left movement. At least on this particular 'defect' of a linear tracker, a solution has been found to overcome it.
The Terminator is a thousand dollar arm! Everything that has been suggested for comparison is in the 5x to 10x category. I would say that the Terminator is an over-achiever, regardless of tonearm type, and leave it at that.

But back to the OP, in re-reading the other posts, the Hyabusa was compared to the top-of-the-line MSL. I would love to hear more testimonies and observations from users, please!

Yes ~ A wonderful cartridge! Into the Sutherland Big Loco transimpedance phono its performance is musically sublime.