mirror cut should work on any polygonal object. You can even apply multiple mirror cuts to a single mesh. Mirror cuts act like deforms in that effects are cumulative. Also to "lock in" the effect you should delete history on the object to remove the mirror cut influence. Below are some sample mirror cuts on various polygonal objects including a torus, a cone, a cylinder, a simple head shape, and an extruded poly profile (sort of a guard rail shape).