I'm with Jennifer -- if they're going to suck on something, it's easier to take away the binky than the thumb.
That said, none of mine has been a huge paci fan, and I haven't really pushed it. My DS1 never once took a paci. He didn't suck his thumb or fingers either -- he just wanted the boob. He nursed for five years.
My DD took a paci occasionally until she was about 6 months old, when she suddenly wanted nothing to do with it. She sometimes sucks her thumb and other fingers, but not much. And, of course, she still likes to suck the boobie.
DS2 takes the paci for his dad sometimes when I'm reading to the big kids in their room before bed, but he has to be swaddled and lying down in bed with his dad with the fan and the white noise machine both going before he'll take it. I don't imagine we'll have much trouble taking the binky from him -- probably he'll wean himself off it like his big sister did.
Edited to add that I saw a baby about the same age as mine today who had a paci in his mouth that said "Mute Button" on the handle. Hahaha.