All of the notes that are missing on the major diatonic are on the Melody Maker. It provides a complete major scale in cross harp for playing exact melody without bending. Yet, the draw notes can still be bent for that bluesy feeling! Melody Makers are designed to be played in cross harp (draw), not straight harp (blow). In cross harp, melodies can be played with an expressive, fluid style that is extremely difficult to achieve in straight harp.
With Lee Oskar harps there's no need to throw away your harp once the reeds are worn. Simply replace them with Lee Oskar harmonica system parts.