Firstly.. I AM one of those old folks !! ( theres till quite a few of us around, still teaching ).
As to PRs many dance on 2, and also 1, is common.. but.. its nothing remotely like Mambo .
Styles have changed ,and many variations from Mambo, never crossed over . The Cuban influence in some styles, is very strong, particularly in casino .
PRs dance a more "blended " style ( what I dance and teach ) has some " slot " and also "circular " , very popular in NY, among other places .
** A footnote on the Son rhythms.. true Son was origianlly written in 6/8 timing.
And today , the Clave is used in a 3/2 and 2/3 based rhythm ,one being a Rumba clave and the other a Son Clave.
Most of the old time Mambo was written a Guaguanco style which is a 2/3 clave, whereas most of todays Salsa, is 3/2.. and the Guaracha which was taught back when, was also a 3/2 clave ( thats the style you will see danced in the old black and white movies, in a Sq Rumba format.. its really more like a fast Danzon )