It is worth remembering, when it comes to cradles and antennae, that sometimes they only boost one of the frequency ranges used by Australian phones. For instance, in the city, 3G runs in the 1200 range, while in the country it is 850, from memory. Some antennae only work in the 850 range, meaning you won't see any real difference until you are out in the bush where that frequency is being used by the towers.
I've had the same problem with boosters, which generally don't give you both ranges...as they are built for the US market.
Carlisle