Arguing about which style is best is a lot like 9mm vs. .45 debates. Far more often it boils down to the person, their understanding of the system and how hard and realistically he or she trains than the style.
That being said, Thai boxing is a great base to build from, with emphasis on powerful natural weapons such as the knee and elbow. I'm not familiar with san soo per se, but, from what I've been told, san soo is included in all combative kung fu as it refers to free fighting.
I'm not familiar with Taipei, Twoblink, but was informed that there was was a very good Hsing Yi teacher in Tainan back when I lived in Kaohsiung.
"I shot an error into the air. It's still going...everywhere."