Plague marines vs chaos with MoN

[Goreshed]

It also comes down to how you choose to use them on the tabletop and what units you are trying to kill with them. Obviously going against a unit of high initiative with power weapons will most likely result in their deaths, but putting them on an objective where they can cover the close end shooty bitz and having something to back them up in the area (like a assault unit of some type) makes them far more effective.