When I actually have to cut a battery or atomizer apart to get the connector, I just dremel all the way through starting about 1/2 down, and then take off just a bit of metal a time from the final 1/2 inch. After its *almost* through, I pry apart the shell with a screwdriver, and if necessary dremel my channel a bit deeper where the actual connector is.
It takes a bit of finesse, but you'll get your connectors out in about a minute completely unscathed every time.