Well I can agree with you about your club theory. I definitely seem to get along best with INTj and ENTp then STs on that superficial level. It's simply natural for me to spend time with those people. The only Alpha SF that I consciously recognized as such is my former roomie and there was that inexplicable bond you spoke of. I mean now that I think about it, we really had next to nothing in common, yet we clicked in a way that was so deep and meaningful that, even though our relationships is pretty much stale (ILI boyfriend came between us) I still can't quite let her go entirely and anytime I see her or talk to her for a time I feel that connection again. It's entirely intangible, but it really is like making up the other half of a whole. It just boils down to them taking care of those things that you value but have to work to provide for yourself.
Perhaps this can explain why a lot of people don't seem to click with their duals on the forum. Because duality is so much deeper than the outward context of interactions with others it makes it extremely difficult to create over something as impersonal as the internet. So instead people will tend towards their club or those that share their emphasis on either their perceiving or judging function depending on which they put more emphasis on. For instance I get the impression that an Ne-ILE like Riddy appears to get along better with other intuitives than he does with non-NT logicals. Whereas I tend to get along better with logicals more than other intuitives. This is all supposition, of course, but that's my general impression.