I currently have a 520XL but the power cord is almost severed right where it goes in to the back of the radio. It is around 4 years old and I have never used the PA so for me that is a non issue. Is the RF gain something that is worth having? I only use my cb when on the trail with other buddies and never use it other than that and my group stays pretty close together when offroad. both radios are dirt cheap but the 510xl is really dirt cheap so what does rf gain gain (pun) me?