I attached this to my Conqueror off-road caravan weighing over 1100kg dry. I bought it to park the caravan in the garage up a slight incline, and found it to work perfectly.
I've kept the original jockey wheel on as well to support some of the caravan's weight and found this to help a lot.
The motorized jockey wheel does a great job of maneuvering the caravan as you need, and has a sturdy wheel, but it has very hard rubber which does sometimes slip if not enough weight is put on it. I'm not sure I quite trust it to take the complete weight of the caravan, but for what I need, it's perfect. Just note, it won't work on grass or sand if maneuvering a heavy caravan - works best on hard paved surfaces.
It also moves nice and slowly and at a constant speed. I find it's far more precise than more expensive movers fitted to caravans, but then does lose the ability to maneuver at the camp site.
Note, the jockey wheel is 50mm and won't fit into the larger 75mm bracket for heavy duty caravans and off-road trailers, but adding it as a second wheel is perfect.