Is there any way to make X Mirror respect delete? I find X Mirror (found in Tool Shelf> Options> Mesh Options) very useful, but it would be more useful if it would mirror my deleting vertices as well as morphing them.

Does anyone know how to achieve this?

Current solution: Delete half the mesh, then apply mirror modifier, but when I have a bunch of bones and textures already in place, it's annoying to re-add them.
I think Carlo's option makes sense, though it might need more explaining. The X- mirror splits down the center and mirrors in the negative X. Any changes you make in the negative, be that deleting or adding vertices will be updated in the positive X after you have applied symmetry. It does not work if you flip the process and work on the positive X first as the negative X will not be updated.