Sorry, but your contribution shows how important research on this topic is.
What’s there to exactly to research?
Let’s start with the first principles: what is a style, how do you define a style and what characteristics determine a style.
I doubt we or any group of independent experts can arrive at a common understanding of what makes a style.
Let’s take example from how you described it.
Salon hold:
-closed at the leader's right side,
-con luce at the leader's left side (aka > or v),
-right to left temple head position,
-independent axes,
-origin in barrios Almagro, Villa Urquiza.
So if the position is not right to left temple head position, it is no longer a salon hold. It is something different? What?
If all remains the same but instead of V, it is parallel upfront, what kind of hold is?
Aren’t all holds closed on the leader’s right side?
Atleast you are calling it a hold and not a style. Which is a more appropriate term. But should hold determine the style?
Milonguero hold:
-parallel chest contact,
-apilado appearence (aka A) with or with only apparent lean,
-right to right temple head position,
-origin in barrios San Telmo, la Boca.
What when it is a V contact with apilado? Pretty common.
There can be any number of combinations of a hold based on:
- parallel or V
- lean or no lean
- shared axis vs independent axis
- head position
- right arm position or close side (high, mid, low)
- distance/daylight in embrace (no distance, upper parts touching or pressed against each other to a little daylight, hence not touching)
- left arm hold or open side hold
Hence to define a style based on holds is largely restricting or even meaningless. Hence codifying a social dancie is taking interpretive and artistic freedom away from the dancers. It is a tradeoff.
Then what is a style. To me it is more like how you dance, step, and move. Less vocabulary, more walking, less rhythm in the steps. Or different style would be sane with more rhythm in the steps. Yet another style difference could be longer steps vs shorter steps. Then we can determine a style of someone’s dancing by their goto vocabulary. More circular or more linearized to keep moving forward in the Ronda vs staying in place. May be there are enough commonalities to define a style in that manner. It is possible that people dancing in the same place (neighborhood, milonga, town) start converging on these elements. Therefore what elements get emphasized or seen to be emphasized in your milongas are different than ones that I go to.
However in street and social dancing if the structure of dance is preserved, then individual styles prevail over any commonly defined style. When the structure is not preserved, then you get something like Neuvo style of dancing (which if we were to get really academic is stage style dancing modified to fit social dance floor). You could preserve the structure but change the music that you dance to it. Imagine traditional tango style dances to non-tango music. Pretty much what happened in the WCS. The structure didn’t change but they started dancing it to almost any music.
That’s if we were to define a style, only a few primary elements or characteristics should be used to define it. Most of these elements are physical - hold, how you move, etc. Then the question becomes does the way you interprete the music or not, be part of element that defines a style. Styles are always fluid. That makes an additional challenge since style is a function of time.
To me only two primary styles are that prevail in current social Tango. Traditional and Neuvo. They are distinct enough to define and recognize when absorbed. Incidently music choices also differ for each style. The rest is all individual styles within and really pointless to sub-categorize.