No I don't. I'm very happy with the free Silhouette Studio software, so I haven't looked at anything else. But I just looked now, and MTC is not free, and it isn't Mac-compatible. So I'll be sticking with Silhouette Studio.
I glad that you are happy with your software. Yes there is a fee for MTC, but once you own it all updates are free. Some cutting machines now come with MTC software as part of the machine. My cutter came with the software. MTC currently has a mac version out for KNK and are working on adding other machines.
Andy the designer is always working on making the program more user friendly. I think this year there has been 3 or 4 major updates. The latest one that I love is allowing the importation of gsd files. You can clean them up and reduce the size of the file without affecting the quality of the design.
Oh and MTC also doesn't seem to be compatible with the old Silhouette even on Windows, and that's probably a show-stopper, since I doubt they'll bother to write Mac software for an old version. Ah well.