The PowerBender (PB) middle octave in any will be the same as the PowerChromatic (PC) repeating octave in that same key, just as a Standard tuned harmonica middle octave is the same as a standard tuned chromatic of the same key. If you mean that learning the PC increases the skill set of playing a PB, and vice versa, then I would say they compliment each other well, assuming you work on building melodies off of the middle octave of the PB. If you tape the first three holes on a PB, and focus on holes 4 - 7, you will pick up the pattern a bit quicker.
Is your melodeon tuned in the key of D or C? If it is tuned in the key of C, and you find yourself playing tunes in D, then what you are doing is playing the 3rd position of the instrument/Dorian mode of the C scale. I see in another comment you mentioned you had returned an F# harp to play with, but also you picked up a Chromatic. Is the chromatic a C, G, or D?
If you are playing a C melodeon on your songs in the key D, and you want your harp to match chord tones of the position/scale, then you may also like a PB in the key of C. I recommend the Lucky 13 PB version. If you want a Lucky 13 PC in C, you have to re-tune it. If you look under may name, and my posts, I believe there is some discussion in this forum on how to do this with minimal changes to the Lucky 13 PC in the key of G. If you go that route, definitely look on here for advice.