FWIW, Twitterrific does have a Mac client. I've haven't been too active on Twitter lately, but my feeling from a while back was that Twitterrific was the better iOS client (and Universal as well), while Tweetbot was the better client on OS X.
Edit: Again, never mind. I just checked the link and yeah, they are way out of date on the Mac version. I'm done paying lazy developers who can't keep their products in line with each other.
They also lose me on proper muting and some of the sync functions between iPad and iPhone alone don't work properly. Muffle is crap. The whole reason I mute people is so my timeline isn't cluttered by certain things at certain times, and with the muffle "feature" not only does it not sync properly between two devices, it also doesn't do anything. You'll still have a timeline full of "___________ was muffled" (can't remember word for word), which is just as obstructive and annoying as the tweets meant to be muted.