Used mine yesterday, in fact. She was a good sized doe, but the cart allowed me to get her out to the road by myself.
Schlaggerman and I did a pack in mulie hunt in Utah many years ago. The seep we were to get camp water from was dried up that summer, so we borrowed a game cart and hauled two five gallon jugs up to where we camped. Of the many questionable things I've done in my life, that has to rate up near the top. Just plain dumb.
To answer the question, ON FLAT GROUND they work great.