well codex wise yes, there are no more limits to that kind of thing at all.
fluff wise...i would say yes as well. The Iron Warriors became really bitter and would be savage once they finally broke into whatever place was under seige. i can see how some would group together into forlorn hopes and these squads would just slaughter their way into the city, eventually going over to khorne.
however, i wouldnt use more then one or two squads of bezerkers. all CSM now have 2 CCW as well as bolters so theres really no reason to have a large number of bezerkers in any CSM army....unless of course theyre world eaters

so yea, theres no reason why you wouldnt want to use them, just dont use alot of them.