Limey,
our hospital has the pressure only (no tank) ones like nost commercial stablishments. We had those put in our house when we remodeled in 1933 and they worked beautifully, even up on the 4th floor. I doubt you can find a toilet with a tank in 90% of Germany.
The trouble is, our hospital is on a hill and they don't have enough pressure to start with. Even for a small pooper you have to flush 2-3 times, so what is the purpose of having them unless you have good water pressure. Luckily, in my part of this metropilis we have high water pressure and even my HET works fine, yet sometimes I flush twice just for the hell of it abd to keep the sewer from plugging up. I try to conserve water in other ways.