I will be replacing my storage tank water heater soon and need advice on whether to go with another tank model or a tankless one. I have an older 2 story(about 120 years) and currently have two 40 gallon heaters. Anyone have a tankless system that has problems? Please share. They seem to be the up-and-coming thing in water heaters but a friends says they get bogged down from hard water buildup fairly quickly and require an acid cleaning of the coils. has anyone else heard of this being a nuisance? Plus eventually I would like to have a multi-headed shower and fear this would not be benefitted by a tankless. But of course i DO want to have the nice energy savings as touted by the retailers for tankless heaters. Any feedback?