I'm very leery about using terms like "LessWrongism" or "Yudkowskian" anything. If the problem with "rationalism" is that people won't know what it means, the above two are worse. People won't know what it means and it will make us sound like a cult.
The problem with "rationalism" is not that people don't know what it means, it's that it means something different to most people then it does to us. With terms like "LessWrongism" or "Yudkowskian", at least people will realize that they don't know what they mean.
You see, I've seen the word "rationalism" used to mean all five of these things at different times:
Edited to reinstate that proposed solution, since this discussion is presumably finished.