I've got both. The wife prefers the trunk due to the higher support and it makes her feel safer. Myself, I prefer the back rest because I mostly ride solo and the trunk seems to catch (or make) more turbulence at highway speeds. Short jaunts with the wife or solo, it's the back rest. For longer rides with the missus, or if there's a possibility of a Costco stop or anything else the saddlebags can't handle, I'll put the trunk on. I've got two carriers, so it's an easy switch. I keep the back rest on one carrier, and the trunk base on the second.