With C you almost always know what you have, and can always cast it to anything else you want (safely or otherwise).

With Go, I'm never sure what I have (pointer? reference? something other and weird?), and can't cast things that should be castable.

Either way, I'd still rather take Haskell or Common Lisp, but I'd gladly take C over Go after having used Go for a highly multithreaded communications server.