Time to choose: Baerwald, Lofgren, Stevenson ?

Lewm:
I recall seeing that white paper online, but have not been able to find it again. If you have a PDF, I'd appreciate it.

The RS-A1 unipivot it supposed to be positioned so that the cantilever and tonearm are parallel or ideally on the same straight line. Since not all cartridges have the same angle for the cantilever (I think they range from ~15 to ~22), this will be an approximation. The limited design info I've found doesn't mention torsion, but speaks of "downforce":
http://www.eifl.co.jp/index/export/rs-a1.html

When we usually talk about skating force, we assume that the cantilever is tangent to the groove and pulled along this tangent (only true at those null points naturally). Since the resulting force is at an angle to the line going from the stylus to the pivot, a sideways force results. If the cantilever is not tangent to the groove, the friction force would still be tangent to the groove and thus straight arms would also have a sideways force proportional to the angle between the stylus and the groove tangent.

I've seen reviews of the Viv Lab in The Ear, Stereo Times, and Audio Beat. All reviewed the 7" version and none of them complained about distortion. Audio Beat said they also had the 9" version, but just mentioned that the 7" and 9" sound different "and not in the ways you might predict". Also Audio Beat mentions that the order was the opposite you mentioned: The designer started with the very long version to reduce tracking distortion and then realized that the shorter ones sound better.

Fleib:
I'd appreciate links to those comparisons of Viv Lab versions too.

It's amazing how far we can go with audiogon contributors, from old '7 inch records to the new '7 inch tonearms. 

Well, i'm testing Lofgren alignment with good results on Victor UA-7045 with Victor X1 cartridge. 

What is truly amazing with Victor X1 is my new 100k ohm resistors that completely change the sound of this cartridge. Hard to believe i'm listening to the same phono stage and the same cart i used before at 47k ohms. 

Chakster, You might consider listening to the Victor tonearm in Lofgren for several weeks.  Then re-align for Stevenson (only assuming that the Victor UA7045 is designed for Stevenson), and listen for another few weeks.  Then decide which you prefer.  A few hours of listening to one alignment is not going to provide sufficient information, in my opinion.

Sampsa, I agree that when an underhung tonearm with zero headshell offset is operating anywhere on the LP surface such that the cantilever is not tangent to the groove, there is indeed a skating force. The only point on the LP surface where skating force is negated (zero) is that one point of tangency.  But the apparent excellence of such tonearms, despite the large tracking angle errors that they can produce at the extremes, suggests to me that skating force created by the headshell offset angle necessitated to achieve any of the 3 major 2-point geometries, and maybe the common strategy for introducing anti-skate, may be in some way more pernicious than is the skating force due purely to lack of tangency.  That's what interests me.

@lewm 

Chakster, You might consider listening to the Victor tonearm in Lofgren for several weeks. Then re-align for Stevenson (only assuming that the Victor UA7045 is designed for Stevenson), and listen for another few weeks. Then decide which you prefer. A few hours of listening to one alignment is not going to provide sufficient information, in my opinion.

That's what i'm gonna do. I think i'm very well prepared for a long winter, it's start snowing and getting below zero degree. I will spend more time listening good music in the late evenings (using different carts and arms). That's the the plan.