Take any non-Fearless Chaos Marine unit, throw a decent IC or monstrous creature character at it solo, challenge, punk champion, make CSM unit have to take a check at Ld7 or 8 or risk getting swept.
Not a big problem for things like IG, where you're losing 70-80pts a squad. There I hope for my squad to break, so I can shoot the offender in my subsequent turn, and the sacrifice is minimal. But for marines where you're talking 2-300pts per squad, that can add up fast.
What do you think? In order to survive in a world of challenges, are CSM going to be essentially required to either go Fearless/Cult or include a beatstick IC in any unit that's going into the danger zone? Or is the risk low enough that cagey playing and a little luck can avoid it, allowing non-Fearless units to perform well in the front lines?