I am replacing an old electric water heater. I was interested in the tankless water heaters because of the energy efficiency. Can anyone who has experience with these units let me know the major pros and cons of these units? I was looking at the Bosch aquastar, the Takagi Flash, and a model made by Paloma. Six people reside in my house: myself, my wife and 4 children. Will a 2gpm unit stand up to the useage or should I get a 4 gpm? Thanks in advance to all who respond! -Dan