Well, it doesn't matter what the FBI are. But what really matters is that it's not RP for a "super" military aircraft to be simply a cop helicopter. Neither is it RP for a civilian to be flying a helicopter which has a built in machine gun which has infinite ammo and can be used as a murdering weapon.
I really wouldn't understand why suspects want more advantages. If people haven't realized, in a chase, suspects already have the advantage of playing an easier role than the suspect. What that is, the suspect's role is just simply run from the cops. This can be done by running or killing the cops. Their task is simple. Cops on the other hand, have a much harder role to play. When chasing a suspects, they're not just simply trying to keep up with them. They're trying to ram them and force them to stop, and then kill or jail them. This alone, is already a major advantage for the suspects. Having cars to run, is already an advantage, however, it is not an advantage which makes it impossible for cops to stop them. Cops can use strageties to stop a running car. And even then, if suspects abuse the foot running advantage (such as jumping), there's a 5 car rule to restrain this problem.
However, adding an attack helicopter will add the advantages to such an extent, roleplaying as a cop will become very irritating because of the advantage of the helicannon use and also the abuse of flying out of the city, or flying at very high altitutes to avoid ground attacks. Since the hunter is for military use only, as it should be, it is almost impossible to stop a helicopter running suspect. If sea sparrows are police helicopters, then a suspect running in a helicopter will not have a further advantage as they can be stopped by this helicannon.
Sea sparrows, though with the helicannon, cannot give the cops a further advantage. They are useless against a suspect hiding in an alleyway, or at an interior because their autoaimm, unlike the hunter, only works at very close ranges. But even then, the main reason is that they cannot find people to suspect.