I have a spotted hawkfish, very close to the falco. I had him in my 180 for a while and he was an absolute terror. Never bothered my shrimp, but they also would not come out during the day with him near. He harrased my fireshrimp into hiding until it eventually dissapeared. I moved him to my 55 fish only and i added a diamond goby and he killed it with in minutes.
So I think it depends on the fish.