Great points. I'm concerned about # of circuits (I don't have any add-ons, just a heater that I don't use, a radio that is not there, turn signals, etc.). I'm also concerned about quality. But mostly I'm concerned about installation instructions. One of the products boasts number labels that correspond to the diagram and circuits. This may be a case where I buy a cheap one, learn my lessons, then buy what i should've bought in the first place but didn't know it. I'm trying to avoid all that.
