The cat curfew has worked well in Australia - South Australia has it. As for limiting numbers of cats per household - I think thats a great idea especially for those less responsible. There should be exceptions to the rule though.

People who foster or care for sick and injured cats
People who can show just cause for keeping more than the said number of cats (like dogs now in Australia - it is illegal to keep more than 2 dogs per household without showing just cause as to why - my parents live on a cattle property and can only keep 2 dogs - this is to stop dumping and ferals attacking domestic animals - over time this may work ...).

Cats kill a large number of birds and wildlife here in Australia. While I love cats - I know that they are an introduced species here and domestic (as well as feral) cats need to be controlled. Bastet is indoors for that very reason. I couldn't bear for her to come home with one of our native parrots dead in her mouth.

I think if you paid for microchipping that should be enough for registration. I don't think paying for registering your cat is going to fix the problem of species predation.

Anyway, I don't mean to cause anyone to get angry over my comments - this is how I see it. We need to be responsible (I know everyone here is) for our pets.

Sorry for the rant ...