Time to choose: Baerwald, Lofgren, Stevenson ?

In defense of the arc type protractor, the converse of your criticism of it is that if the P2S distance is not precisely correct, the arc type will tell you that, and you can fix the problem.

If the tonearm is 1mm too far and you mount the cartridge 1mm forward so that the overhang is correct, can you really tell the difference between an arc with radius of 270mm vs. 271mm? The difference is going to be tiny. Notice that this is different from having the tonearm mounted right and having the overhang off by 1mm.

The good news is that the effect on the tracking distortion is also very tiny, shifting the null points by less than 1mm if the tonearm is 1mm too far or too close but overhang is right:
http://www.vinylengine.com/tonearm_alignment_calculator_pro.php?arm1=Arm+1&l1=ps&a1lv=271&am...

Lew, I've been happy with a Dennesen for alignment for years.  I find it so much faster, easier, and therefore more likely to be correct than 2-point arc protractors, such as the DB Systems I used previously.

However, I do utilize a good light and small hand held magnifier, then I have no problem seeing when the stylus tip is in the dimple and the cantilever properly aligned with the guide lines.  Mine are not faint, just tiny. ;^)

Lewn,
Maybe you are right by the way. I had the Unidin curve for 3 days but it still is a short time. Yesterday the Loefgren was used with the same records for a first comparo. 
I admit I have been a bit impatient. Now I want to stay a few weeks with the Loefgren before trying the UniDin curve again and make a more definitive opinion.

Dear @barbapapa : Overall Löfgren " A "/Baerwald and Löfgren " B " has lower distortion levels than the other alignment you mentioned. That alignment is not something " special ", it's only a manipulation of one of the input values in the alignment calculation formulas: the change was that instead to take either: IEC or DIN  or JIS standards value for the most inner groove input it tooks 54 with no real overall improvement. As you, M.Fremer voted for Löfgren B too through his tests.

As I posted  what any one of us need as a protractor is the MINT LP one, that's a dedicated protractor for the TT/tonearm we own. It's really accurated and for only 100.00-150.00.
 IMHO no one needs more, is really useless stay trying any other protractor other than by curiosity. At the end what we music lovers want is listen MUSIC all the time and not testing 3-5 diferent kind of alignments. Again: useless.

Btw, @lewm posted: """  curve again and make a more definitive opinion. """.

You tested by 3 days and changed to Löfgren with the same LPs. IMHO you need no more. Your ears telling ( in this case ) what the numbers tell it too. 

We can think that a short/brief time can't be enough and sometimes is true but when one person ( as you ) knows what to look for that times goes lower.

I don't need to many time to give my vote to Löfgren and Baerwald over Stevenson alignment: 2-3 hours can be more than enough. Why can I follow wasting more time? when what I want is to enjoy MUSIC. Makes no sense to me: makes sense to you?

Regards and enjoy the music,
R.