Guy, have you trained SPM, Pak Mei or other Hakka arts?
Yes I have. Not any more though
They are not widely taught here in the States, so I only know what I read or see on Youtube (i.e. nothing).
I think probably more in US than in some places. Robert Chu will probably know where to find it if you have any contact with him. UK has quite a lot due to HK Chinese population.
Anyway some people have opined that WC may be influenced if not partially derived from those arts due to many shared traits such as the short stance and emphasis on infighting, arms held in front with the elbows down, the rounded back some WC branches also have, ample use of the "phoenix-eye fist", as well as geographical proximity in Southern China.
I would say they work in completely different ways. They look superficially similar in some ways, but for me they are not. Compared to these systems, wing chun is like a step change, an evolution. Wing chun is fast and mobile. Hakka arts are not so much due to more involved body mechanics. I guess they would claim striking power over wing chun but they lack the momentum based power of wing chun. Wing chun is economical, attacking. Hakka systems are more complex, counter punching styles.
Also, you again referenced "float, sink, swallow, spit" which I've also heard in Okinawan Karate circles. In your experience, do these principles have a place in WSL VT? Or do you feel they contradict your WC structure, principles for power generation, forward intent, etc.?
I would say that they are contradictory. Wing chun power connected is like a spear point with the shaft stuck for a second against the ground. It is momentary and explosive. It doesn't need prolonged contact. Hakka systems are more trapping/semi grappling systems that draw the opponent into a place where they can be destroyed. They rely on contact and not too much moving around.