The Mystic is a great 9mm can that just so happens to be adaptable to several other calibers. As a .22 can, its grossly overbuilt and will look/ feel out of place on .22 host firearms. As a .223 can, the efficiency suffers due to the larger than necessary bore diameter. .223 rate of fire is also limited to prevent over heating of the components which were primarily designed for handgun use.
Due to its size and weight, I think a Mystic would make an excellent subgun/ 9 mm SBR can. For pistol use, it will work exactly as intended, but the average 9mm can on the market is shorter and lighter. HOWEVER, if you plan on suppressing .357 Magnum, the Mystic is going to be about your only option. Keep in mind that the super sonic crack from .357 mag ammo is still going to be quite loud.
Edit, Ive heard that an Octane 45 is capable of suppressing .357 Magnum when fired from a carbine length barrel. The extra volume of the .45 can is what allows this. An email to Andrew @ Silencerco might be a good idea just to confirm. An Octane 45 is still 4 ounces lighter than a Mystic and adds the ability to suppress .45 acp, though you will lose the capability of suppressing .223.