I'm a bit late on the discussion, but one advantage that I can see is that Hipache adds the HTTP_X_FORWARDED_FOR header, something that the Haproxy author refus

I'm a bit late on the discussion, but one advantage that I can see is that Hipache adds the HTTP_X_FORWARDED_FOR header, something that the Haproxy author refuses to do (perhaps for good reason, I'm not sure).