Should I get 300 blk

I have 11.5 and 16 556 for close/HD and anything further than that. I have 9mm sub gun for close/HD suppressed shooting. My main question is will 300 blk out of a 9 inch barrel give me anything I don’t already have. Like quieter or substantial amount of power increase compared to 9mm using subs. Or something that will have better ballistics or maybe quieter than my 11.5 with supers.