invisible grill doesn't works well with dsl as you can easier cut off the wire.
of course, you don't expect to attach 1 alarm sensor per wire right?

wow... 60 bulks psf? that's very expensive
anyhow, people will still get in even your house with alarm, grill or what so ever gadgets that you may put it
just need to be careful by keeping your valuables away. perhaps a home safe deposit box?