We are all aware of Google's approach to introduce ChaCha/Poly1305 as TLS cipher suite. The rationale seems clear: ChaCha is newer and seems to provide better security (and maybe speed?) gained from the experiences of the design of Salsa20.
But in his "recent" paper McBits: fast constant-time code-based cryptography (basically code-based ECIES) Bernstein (the inventor of Salsa20 and ChaCha), Chou and Schwabe used Salsa20 as standard primitive for McBits and not ChaCha.
So what are the reasons to prefer Salsa20 over ChaCha?