The piano tilters work great; they're a required tool. HOWEVER, I did run into a big problem when I was replacing metal castors on a Yamaha U-1 piano. I had tilted the piano, and put on the rubber, double-wheeled castors. I started to tilt the piano back to vertical. When the rear castors contacted the floor, they worked too well and the piano literally rolled off the tilter. With a LOUD bang, the piano ended up on its back on the slick tiled floor. I was working in a classroom right above the library and one of the librarians dashed up to see what had happened and if I was okay. I was fine, but the piano wasn't. The aluminum action rail was bent and the lid was damaged. Both were repaired without much problem.
There are two takeaways from my minor disaster. 1: check the bottom board. Yamaha U-1s of that era (and maybe still today) have a bottom board that is recessed from the back edge of the back of the piano. This means that only the tips of the tabs on the tilter touched/contacted the bottom board. 2) Before tilting, strap the tilter to the back of the piano with movers straps. It's sort of a hassle, but it guarantees that the piano won't slide off. I had used the tilter countless times before that without straps and without a problem, but the construction of the U-1, the slick floor, and the new castors conspired to bring down the piano.
Richard West