Hey Dave. Sorry. Not sure what the difference is between "Visitor Messages" and "Private Messages". Sorry I lost your first message.
The trailer valet is fantastic on flat ground. You can steer the thing very easily and maneuver wherever you want to go with precision.
Inclines are a bit different. I think the Trailer Valet spec. says you can use it up to a ten degree incline. There is also very fine print that states you MUST have the tongue on the downhill side (forcing the weight on to the trailer valet). I thought it was just liability BS so tried backing it down my driveway with the tongue uphill. I left the boat trailer safety chained to the truck just in case, and set some wheel stops. Without those precautions, I might have had a tough time getting the trailer to stop rolling - the trailer valet wheel was just sliding on the ground, with the brake fully on.
I've tried in on slight inclines with the tongue (and trailer valet) on the downhill side, and it worked. It started loosing traction as the hill got steeper, though (probably greater than the 10 degree recommendation).
So there you go. Great product for flat surfaces. Be careful on inclines and stay well inside the recommended parameters.