When I lived in Japan, the last two places I lived, (Osaka and Toyota City - 21 years total) we had separate tankless at each bathroom and also the kitchen. NEVER had problems with them and by being at each location, hot was always within 3 to 4 seconds at the faucets/showers. Saved water and saved gas. Here in the USA, most people think of one central tankless,. It does cost more for individual locations in the house, but for the long run, the ROI savings is there, AND no 10 to 12 second waiting on the hot water or or wasting cold water.