Jay z has as least one RM. that said, I think Jay-z is in a different level of class compared to guys like Rick Ross. Depending of who they are "sponsoring" watch wise, it may or may not be a wise decision. The market for luxury watches is inextricably tied to the market for high end fashion, which is in a lot of instances very enmeshed with the rap scene.
Regardless of how AP got to be popular in the rap scene, it has become the new "it" watch, at least I'm part because they are big and gaudy. Comparing them to RM doesn't work great because RMs are at an even more prohibitive price point, such that even the most frivolous up and coming rapper might think twice before blowing their advance on one. I would be willing to be that if AP had been giving out RO chronographs to rappers instead of offshores, they wouldn't have taken off in the same way.
Point being, watches like the ROO are designed and marketed for people who lean towards conspicuous consumption (people who live in Miami talk about seeing them all the time, I haven't seen one in the wild in the suburbs of DC, where there is plenty of money but it's a much less ostentatious culture), so even if they didn't market towards rappers they are still more likely to be worn by people like rappers than, say, an ALS datograph. Considering the general market for the ROO line, the decision to use rappers as marketing may or may not turn out to be folly.
