jac, I've drilled many aquariums with a diamond tipped hole saw. Plain glass bottoms. Nowadays most aquariums are made with tempered glass bottoms and the manufacturers warn that they will fracture if drilled. Think of what happens when the tail of a Prinz Eugen drop is broken or even just scratched.

If you must have holes in your rare filters, please try to find a common version that you can try drilling first.