@Gerri:
Is his music now more like Sanji's recipes (that he probly got from the okamas) enhancing the skills and features of the other crew members. This has at least been hinted at in the satan story. Or is it more like a weapon, as we have seen the sleep song before. Or is it merely entertainment as pirates love to sing and dance and therefore more like Binks sake.
I'm guessing it will be all three. In his back-story, Brook was shown playing music to help his crew, to entertain them, and to defend himself – so all three aspects have been integral to his character from the start, and will hopefully continue to be so.
I also think that Brook's switch from acoustic guitar to electric guitar hints that he' now aware that amplified instruments can affect a larger number of people. So just a switch from acoustic to electric can be considered a "power up" of sorts. But I don't think he'll ever abandon his acoustic instruments either -- he'll need those for battles in areas without electricity, and for happy celebrations with the crew.
At least, we can say that the pirate king has the most famous musician…
Heeeey! That's right. Niiiice!
Mortea: Too Much Information. Sheesh.
That aside though, I do like your thought about Brook enhancing the rep of the SH by "joining" them after having become Soul King. I don't know if the Marines would be able to connect the dots between Brooks former bounty poster and his soon-to-be-current one – and it's possible that he, Sanji and Usopp will end up with two bounty posters apiece. But I hope not.(Especially in Sanji's case -- because even though that poster is a blow to his ego, it keeps him from being recognized when he's sneaking around).
Just as long as Brook's fencing doesn't end up ignored completely for music. If that ends up being the case then it'd be a big disappointment to me since through Ryuma we at least got to see some of what he can do.
I'm guessing (or maybe I should say "hoping") that the only reason why we haven't seen Brook's fencing so far is because his sword/can was taken away by the slavers. Now that he's a world famous superstar though, I'm sure he's either got it back from them or bought a new one.