The wiki, as far as I'm concerned, is only useful for getting a general idea of what FET is. As you noted, it is completely devoid of any proof and is merely a bunch of statements. Further, not every REer believes all of the stuff in the wiki. It's really a mess.
Proving things is almost impossible. Tom, who posted above, is notorious for demanding levels of proof that simply aren't available to your average person. Now, if it is something that he feels benefits FET, he will gladly accept it with no proof. I've also seen him post several youtube videos as proof of something.
My gut feeling is that demand for proof is really the only thing FEers have to defend against some really good points being made that invalidate FET. GPS is a great example. Tom likes to demand that we prove it isn't using "round Earth assumptions." The obvious answer is, if it is using round Earth assumptions and it works to an amazing degree of accuracy, it must be using the proper assumptions. So yeah, if you're asked to prove something to a level that's not reasonable, you're probably winning the argument.