I was just about to link to that thread-since I was like, "Ohhh yeah, I have a thread to link to for this topic!!" So I'm going to give the same link as PB just so I can say I did. http://www.17thshard.com/forum/topic/7900-other-shards-invested-in-stormlight/#entry132351
I like the part of the theory pertaining to the surges being polarized towards the two shards, however the rest seems a little loose.