Sounds like straight forward advice John. Your not the Brian tankless guy I was thinking of.
By the way, what is the price, size, first hour rating, and btu rating of the unit you mention above at 5 gpm? That way she can compare your advice with what she is being offered with her house(apples and oranges) in case they are offering her a lesser model?
I'm using a 50 gal, 40,000 btu natural gas wh with a 74 gal first hour rating and would like to compare also. 5 gpm may work for us. Also, how long does it take to get the 5 gpm flowing from the time you turn on the shower and do they have any type of storage tank? Thanks in advance.