We bought the Rand McNally unit a couple of months ago. The first one we got from CW was defective out of the box. We took it back to the local CW store, and got a refund, but they would not reimburse us for the shipping (we ordered from the website). CW didn't have another one, so we ordered again on line. This unit worked well, but there are some things you need to understand it.
When you set it up for your RV, there isn't any guidance. Our FW is 30 feet, and the overall length of our TV and FW is 47 feet. When we were programming the unit, it asked for the "length of your RV and Trailers". We put in 47 feet. We took our first trip with it, and it kept routing us on very strange routes. Our Garmin, plus several mapping web sites routed us the way we naturally would have gone. It also kept trying to route us down these tiny little dirt roads. I was fed up with it, and tried to take it back to CW, but since we'd tossed the original packaging, they wouldn't take it back.
I posted a really bad review of the unit on the CW website, and within a couple of days, I was contacted by one of the supervisors at Rand McNally to try and figure out what went wrong. By programming in "Fifth Wheel" and "47" feet, the GPS software assumed that our trailer was 47 feet, in addition to the TV. So it routed us on highways that were designated for commercial trucks. I changed the set up to "30" feet for "RV and Trailers", and it then routed us on the path we believe we should have used.
When it came to routing us down these little dirt roads, there is a preference that is buried several screens down that allows you to "Avoid Dirt Roads". Once that was set properly, it no longer tried to send us that way.
So, we're going to try it again, and see if it meets our expectations. Wish us luck.