The way i see it, flamers are more effective than jackals in small numbers. Flashbang shines in these cases and and the flamers can better close ground under these circumstances. BUT, the more you get, the more jackals shine, they get better in numbers--flamers, not so much.
Frankly, I like jackals better, but they each have reasons to use em and reasons not to.
Scarab: "Oh little unimposing marine in my way, would you please step aside, you are so much shorter than the mountain I just climbed over, yet I just can't seem to get by you. It isn't like I would be able to step on you or walk over you."
Carbine>BR