dkm,
in *my* humble opinion, San Shou fighters have slightly better chances of winning fights against MT guys on the ring becuase they cross-train. (they use San Shou takedowns, MT kicks & knees, and sometimes boxing skills)
I, a 7-year Muay Thai practioner, do western-boxing because I know the importance of cross-training. (As a result, I have become a much better stand-up fighter)
However, I *HIGHLY* doubt that San Shou fighters can win the fight against Thai fighters such as Namsaknoi (258 wins 12 losses) , Samko (or Shamko... 298 wins 22 losses), Fuakao or Chokdi.
If you'd like to see their pictures, please go
http://www.koma-gp.com/index.php?CASE=kingdom#
Namsaknoi (first left)
Samko (second left)
Fuakao (third left)
Chokdi (fourth left)
Enjoy... and just wanna say that NOTHING IS GREATER THAN CROSS-TRAINING! This idea has been proven to be true by UFC, K-1, PRIDE, KOC, and many other MMA competitions.
I love Muay Thai, and I promise to myself I won't stop training in MT until my body stops functioning completely. And I dare to say that if you add western-boxing to MT, you have a better chance against other stand-up forms such as San Shou, Kyoukushin Karate, Kickboxing, etc.