You know, I think a lot of this stuff really misses the mark. I would say that I agree with many of the LW "mainstream" beliefs, generally find my posts being upvoted, have attended meetups before and enjoyed myself, and so on-- but I've never tried nootropics, I think cryonics is an expensive way to buy optimism and signaling, I'm fairly sympathetic to religious groups, and I've said so explicitly several times without any real fear of retaliation or even downvoting.

As long as you express your opinions in a reasonable, self-reflective, and well thought out way, I've found you have nothing to worry about here, and that's really not the case in most other communities I've participated in. What are the "heresies" of the LW/human rationality community? It's hard to say.