It's a situational question. If I am the fc healer, we are 0-0 and know there are 3-4 rogues that may team together to sap me, wait for others to leave me alone like lions on a buffalo, well it's trinket + feral displacement. If not, trinket is reserved for ship or fear when there's inc in base.
Edit: me, always getting spell names wrong.
Edit edit: to be clear, it's noobish if there are only 2 rogues around that are not 24, as a healer one can overheal the initial burst, or in general if you are dpsing, better leave the trinket when one is nuking the efc.