Can we know the evolution of Siu Lin Tau the set?
Yes, by observing the snake and crane section of the Siu Lin Tau across lineages we can see a trace.
first,
Take a look at the snake reel section of these lineages. from YKS to Ku Lo to Chan wah shun to Snake Crane , which is the older WCK lineages of the pre 1900.
http://www.youtube.com/watch?v=PDpx5juWHX0
http://www.youtube.com/watch?v=w6Ap3Hgfbqs
http://www.youtube.com/watch?v=bmXWjKPYIts
http://www.youtube.com/watch?v=Tj5OElGZCgU
http://www.youtube.com/watch?v=_IEej1FpJwo
They all shows a snake reel section which is core in the sup jee sau type .( the section before the so called Sam Bai fut 0r Crane section.)
Ku Lo is doing the crane before snake, but both snake and crane are there. the sup jee sau is there. the five fingers trace taiji circle is there.
Now take a look at the snake reel section before the sam bai fut section of the Yip Man lineage including the TWC.
http://www.youtube.com/watch?v=I7M_W35NyYQ
http://www.youtube.com/watch?v=Q6UUx...eature=related
http://www.youtube.com/watch?v=jUr10LZAzh0
http://www.youtube.com/watch?v=crmGYEvLVcw
http://www.youtube.com/watch?v=oJZ9dXiLM7s
So, from the above one sees GM Yip Man's signature in evolution.
the snake reel section of Yip Man lineage is evolved from the Chan Wah, YKS, Ku Lo type of Sup Jee Sau based snake reel to a single huen sau.
From the above we know, the Huen sau type is a post 1900 Yip Man evolution and
as for the 1800 or pre 1900 version of WCK there always a sup jee sau type of core.
Thus, if one freeze time today and take a look at one's SLT, one can use this snake reel section to see how old is type of SLT. To the minimum the pre or post 1900.
if this snake section is lost totally, then the slt is not complete. as we know, even in Ko Lu which is not practicing set. Leung Jan still keep the snake reel and crane withstand as evident in GM Fung's clip.