For lightweight items the command strips, particularly the ones designed for picture hanging, work fine.
For heavy items like a mirror, my personal preference is to use something like these flush mount clips
at the top of the item and the command strips at the bottom.
One interlocking clips screws to the wall, its mate to the item being hung. The clips interlock and take all the weight. The command strips at the bottom simply need to keep it from flopping around. Usually just one clip pair at the top is adequate even for a large piece of artwork. A heavy mirror might require two sets. A command strip in each of the two lower corners completes the job.
This is the same type of product used by Entegra to hang the factory installed artwork and mirrors, except they use stapled on velcro at the bottom which I find annoying (why create all those staple holes when a command strip will do the job nicely).
While the screw on clip approach does require screws (and therefore holes in the wall) near the top, your wall hanging will never fall off. Entegra interior walls in most instances are 1/2" plywood so there is something solid for the screws to hold.
If you ever need to cover up the holes they can be made near invisible with some matching seam tape available from Entegra parts.