Pretty sure they are worlds apart. Mezzer Pro has lots of very trick things going on with the IRT etc, and is apparently notably better than the Mezzer Expert. I never looked into a Mattoc but I'm sure someone one the web has done a feature comparison between the range.Yes, thats the one I'm looking at. Have you tried a mattoc? If so is the mezzer just like a bigger mattoc or something better again?
And as @Oddjob says, Mezzer is fantastic for smashing into things. Amazing on mid and big hits, top end supple is harder to tune for. Apparently the more travel you run the easier it is to get it right.