When we ran into someone who had run the wrong wires before finding out what was actually needed (WHY do people do that?), they had to core through the slab.

So the question becomes: when you say "slab," do you mean ground floor with no space below? In our situation, it was a concrete floor, the 8th floor to be exact. Coring through was costly and irritating to the people below, who had to clear the area to prevent damage.

But WIRE is better than RF. If it's not better now, you risk having this exact problem again when some new technology interferes with the answer you've come up with. This is one of those problems where there's a limited cost of making it work one way, but if it stops working, there's a HUGE price to fixing it. Bite the bullet right now.