Hi Lynn,
If you read many of the postings on these forums you will see that many caravanners sing the praises of most makes of movers, so on the whole they are one of the best ideas of recent times. They especially help the less able caravanners who other wise would have had to give up on one of their pleasures and freedoms. You will be aware there are basically two generic types of mover, the tow hitch systems, and the main wheel systems.
All movers can develop enough power to move a caravan, but it is the ability of the mover to grip the ground that is most important. It is a physical fact that hitch mounted devices cannot not grip the ground as well as the main wheel devices, simply because of the force (weight) that pushes them to the ground. The hitch variety only has its own weight plus the nose weight of the caravan, where as the main wheels have half the weight of the caravan on each wheel! On the flat this is not a problem, but on slopes it potentially very dangerous.
My concern in your case is derived from your need to move the caravan on an incline. If you cannot stop and hold the caravan on the slope JUST ON YOUR OWN (without the brakes being applied), then I would be very suspicious about any of the hitch mounted movers being able to control the caravan safely on the slope.
I personally favour the main wheel systems because of their enhanced safety in operation and overall ability in difficult terrain. They are also available when you get to your holiday site so you can just position the caravan for levelling and getting the best view.