My husband and I were able to move a very heavy upright piano from one room to another over a ceramic tile floor. It required a little bit of adjusting the wheels when crossing over wide grout but not a big deal.
I was skeptical, but decided to order based on the reviews. I have an extremely heavy sofa and it worked great. I didn't need to move it, but I needed to raise it to put a brace between it and the wall so it wouldn't slide. It was amazingly easy.
I used this to move a stacked washer/dryer unit from a cabinet in the kitchen. It worked very well! The washer/dryer unit was rated at about 425 lbs. and I was able to easily get the trolleys in place and roll it out.
These little guys worked great. We were painting the walls and needed to move the furniture away from the perimeters. We put them under a large wooden desk that wouldn't have been possible to move with just two people. Great stuff