This is one of the few places on the net where cryonics related topics are discussed in a coherent manner, particularly by people in my age bracket. And I like that while it's cryonics friendly, it's not about cryonics. It's about the (supposed) rational benefit of cryonics. Not just any cryonics related topic gets discussed, and not just in any way.

I can see how the community might grow to a point where the different topics cannot all be discussed in the same place. The current division between discussion and main is already helpful for distinguishing formal versus informal discussions. Perhaps sub-groups for cryonics, decision theory, existential risk, etc. are good ideas. But separating them out runs the risk of creating trivial inconvenience to cross-pollination of ideas.