I don't plan on carrying it. I have a PLB.Several years ago, I carried an aircraft radio in order to call for help when out hunting. When I had a problem with the engine, I called every airplane I saw. Not one of them heard me. After I got back to Anchorage, I found they were all on the local flight service frequency not 121.5.
I decided to go to the Emergency Control Center. They were talking about a 121.5 ELT that had been transmitting for two days. Sense there was no overdue airplane there was no reason to check it out because of all the false alarms.
I see no reason not to carry a 121.5 ELT unless you're in a hurry to be rescue.