You know what though? I think all of that stuff is cool, but little of it is a solid recommendation for the OP. It's all music for musicians, pretty obscure choices for a cover band's book. All awesome music though.
The thing is, as far as funk goes (at least by my definition) there haven't been many songs that everyone would know that were made in the 90s or after. R&B? Definitely. Pop and rock with funk influence? Sure. But actual funk? Not so much. It seems like he's got plenty of stuff that folks already know and like so why not mix it up a little? Again, if he wants real real funk post-80s, his band doesn't have much of a choice, lol. And, like bass12 said, playing the right song at the right time at the right gig can have a nice effect on the crowd even if they can't sing along.