When I got my trailer, I was originally set up by the dealer with a Voyager. I was never happy with it as it never was completely smooth at stops. I looked at the Primus IQ, P2, and P3. Confused I emailed Tekonsha. He verified the Voyager, as was the original Primus, were pendulum based. He also verified the workings of the Primus IQ, P2, and P3 are the same except the mounting restriction on the IQ and as you move from the IQ to the P2 and then to the P3 you get more information on the readouts and diagnostics. I went with the IQ and never looked back. It is set it and forget it. Head and shoulders, at least in my case, over the Voyager. It is very cost effective and works great unless you want more information. Personally, I just wanted it to work. Many people overlook the IQ because of bad information.