The main advantage of tankless water heaters is the fact that you cannot run out of hot water, no matter how many people shower.
In Europe this is even worse, since our typical tanks have reheating times of up to 4 hours. Typical tanks around here (for a single family home) are 150l (roughly 40gal.) and either 1500W 230V or 6kW 400V (3 elements). In Germany electric tankless heaters are fairly common, usually being 35A 3ph 230/400V. In Austria they aren't, because all our power companies will flat out refuse to connect such large residential loads (if the #@*$ thing alone draws more current than your service supplies you can't just connect it without asking).
