The Caldera and Chelsee are of a different class than the Rhythm and the Hartford. The latter two are more so Watkins and Sundance's value line, so they should be in line with entry level pricing and be less than the other two. Because of that, you'll find them to be a little less energy efficient, less jet variety, and a shorter warranty.
However, all the tubs are of a reputable manufacturer. Great quality all the way around as long as the dealer backs you up!
