Almost. Gunnery commandos/Arsenal mercs should use the kinetic relic, and Combat Sentinels/Carnage Marauders should use the energy relic, because of extra armor pen these specs get. There may be others, these are just the two I'm aware of.
BiS relics sometimes has to take in acount the spec\class you are using
in a smugler class DF the BiS is the internal one, but in SS spec is the kinetic