Hearing Aid Induction Loops

Does anyone out there in Perth theatre-land (or further afield) have experience with induction loops? I've done a bit of research, and the technology looks fairly simple. What are the pitfalls? Are there local equipment suppliers? What costs are involved? Is it worth the effort in a 120 seat theatre? Not being a hearing aid wearer, I would be interested in the opinions of those who benefit from induction loops.