From what I've heard, 4Kids didn't drop Ultimate Muscle. There was only one season in Japan, the second season was made for America.
I really did not mind Zeff or Sanji's voice very much. The only problem with Sanji's voice is that it doesn't match up when he is talking to Nami. His voice is supposed to rise and there should be a big difference between how he talks to Nami versus everyone else.
I thought Dr. Girlfriend Sanji was very inappropriate, but like you, I didn't mind it as much as Uzoppi's. But when he started talking to Nami, all the bells and buzzers started going off in my head "BZZZ WRONG PLEASE TRY AGAIN".
I think the reason why more people are freaking out about Sanji's voice is because Sanji in general has a lot more respect and is seen as "cool" whereas a lot of people already think of Usopp as an annoying dork. :rolleyes: I think that both of their English voices really skew their characters into something they're not.