Ronnie
There is a difference, whether you call it an advantage depends on your inclination, and to some extent what Fred says above about what kind of player you are, although I would modify what Fred says to say ear and feel players rather than just jazz players. These kind of players are less inclined to stick to a pre- set arrangement, and often use the registrations for a fixed selection of favorite voices. The advantage is that these are always the same, and available in addition to the OTS and you always know what to expect without a cheat sheet when you select one. Using the registrations for selecting styles, changes, intros etc, means having a cheat sheet marked up for every song and pretty well sticking with that. This may not be necessary for players who seldom need music, or like to respond quickly to requests. Some players might also use both systems, reserving the registration method for a few more complex arrangements they play regularly, but 'free wheel' most of their music using the other method.
Mike