Minor breaks probably do not matter. But removing it entirely may have some consequences.
In Infiniti models, this is often part of the heat management system - without it, the airflow on the engine is not probably not as originally designed. But, strictly speaking, we do not know how critical this is! If it breaks to the point where it has to be removed, most previous advice has been to replace it.
BTW, the heat shield being left off(!) after oil changes on first-gen Infiniti Q45 has been one of the reasons not to take the car to Jiffy-Lube (and the like) quickie oil places!
Check with Joe Tsensky at
http://www.everythinginfiniti.com to see if he can get it for a better price for you.
Z