Koetsu cartridges - what arms work?

Racedoc, This is in response to your post of 10-13-2017.  Therefore, you may never see it.  I am not sure exactly what Peter Ledermann may have told you regarding skating force and the Viv Float.  But it most certainly does generate a skating force at all points on the LP surface except that one point where the arm wand (and presumably the cantilever/stylus) is tangent to the groove.  At that instant, skating force = 0.

Conventional tonearms can achieve tangency to the groove at TWO points on the playing surface of the LP, which is the whole reason for stylus overhang and therefore headshell offset angle.  However, even at those two points of tangency, there will still be a skating force, due to the headshell offset angle.

What the Viv and the RS-A1 may be telling us is that our obsession with tracking angle error is misplaced.

I ran a Blue Lace on a 12" 3DR arm, worked but far from optimal results.  You can purchase a great condition FR-64S for $2500 that works excellent with Koetsu.

I have used a Koetsu as well as my current Kiseki Purple Heart Sapphire in a Well Tempered arm, and although th WT is rather pedestrian compared to some of the heavy iron here, both cartridges have proved to be an excellent match.

@lewm 
The skating force changes the direction using the ViV Rigid Float.

At the "lead-in groove" (the start of an LP) there is a very weak
force to the inside.
Most of the part of an LP there is no noticable force (even with a
flat / non-grooved platter no movement).
At the "lead-out groove" (the end of an LP) there is a very weak
force towards the outside.

In average the skating force is negligible compared to a "normal"
tonearm.

I have heard many fine systems utilizing Koetsu cartridges, but, I cannot say to what extent the particular tonearm contributed to, or detracted from, the sound I heard.  A local dealer that is particularly fond of Koetsu cartridges likes the Ortofon RS-309D tonearm (12" tonearm that can accommodate a SPU-type headshell).