What about Uni Din?

I for got to mention that the way you do this micro a microscope is under high magnification you orient the stylus so that the long axis is perfectly horizontal. Then you back off to low magnification and the cantilever should be perfectly vertical. I have an eyepiece with a grid so I do not have to guess were 90 degrees is. Regular microscopes are not the best tool for this job. 

Darn, I must be going crazy. I'm beginning to understand Raul.

Thanks guys. I'm will try to evaluate it but not having two arms at the moment might make it difficult. My own feeling is that for the vast majority of records ending by 65mm Lofgren B is going to be the best.
Raul, the inner null point of Uni Din is at 63.3 mm. 
jtimothya, I do believe Mr Fremer's graph is mislabeled. The Y axis I think is degees of error not Harmonic distortion although the two are most likely related. Notice at the null points it is listed as Zero. Harmonic distortion is never zero.
If you were really interested in inner groove error I think you would go with Stevenson. Some of my older classical records do run darn close to the label and the big crescendos are always at the end but this represents maybe 1% of my listening. I love string quartets.  

@lewm , I think if you look at phase angles with a given tracking error the phase angle difference between the left and right channels will be three times greater at the very inside of the record than at the very outside. Because the outside is traveling three times faster the peak to trough distance at a given frequency will be three times longer. This makes sense to my meager brain.
@rauliruegas , Are you saying the label edge is at 54 mm?
@intactaudio , I examine every stylus under a microscope. If it is not dead on the cartridge goes back. The beauty of the Smart Tractor over priced as it is is that is has a really nice magnifier making it significantly more accurate than the Feikert. Does it really matter? I seriously doubt it but it makes me feel better.

Dave you are absolutely right. Under magnification ( I use a medical microscope with special lighting) The best you can do is confirm zenith relative to the cantilever then you have to get the cantilever parallel to the protractor lines all by eye. So, there are multiple sources or error some, such as the cantilever alignment to the coils are unseen. All you can do is hope to get close. I should have said, "dead on as far as I can see."
Then next question is does it really matter? I use Lofgren B because it results in the lowest average distortion over most of the record. The reality is you can be a little off one way or the other and very few people if any would know it. So why even bother? I'll tell you why. It makes me feel better and my psyche will think things sound better. Perhaps I will limit record wear.

Testpilot, sort of. I have used the DB Systems protractor for ages. $45.00
However with aging eyes I am having trouble seeing things. The Smart Tractor has a magnifier mounted to it that by all accounts works well. That is the only reason I made the plunge. Having just spent 19,000 on a record playing apparatus I want to get what I paid for.  

Thanx Dover. Well said.