I haven't tried it actually, but I bet that trying to maximize 5 stopovers + transits + open jaw would be more beneficial if done with multiple carrier award, than in multiple one way awards.

Has anyone done this trip already?

I was taken aback at first because current regulations allow only 5 'stopovers'. I originally thought that I could go as many cities as possible (ala oneworld explorer), until I realized that 'stopover' meant 'cities I can visit'.