I've started learning Slap in 1978. In 1979, during some regional band competition, I've played one bass-line for the competition by using the Double Thumb Slap technique.
I was young, selfish (some musicians from the local conservatory criticized me using Slap in a Moody song).
Only decade/s later, I've found out that Victor Wooten INVENTED
the Double Thumb Slap.
Suddenly, a year later, I've heard Mark King, but my Double Thumb Slap technique could not produce/imitate Mark's Slapping. It was a DIFFERENT way of Slapping - just a very trained and flexible wrist, plus the thumb.
Please, don't forget the Great Stanley Clarke with his "School Days". It required some brain freedom besides just the Slap technique.
Long story short, I don't like the way Brian Bromberg slaps, but I a very big fan of his Music!