Hi
I think that part of the reason why folks over here (UK) are reluctant to turn downwind below 1000ft (or whatever the circuit height at your particular field) is the fact that they could pop up in front of traffic joining onto downwind (from downwind/xwind/dead side)
Dont know about Oz but obviously the US join at 45 degrees to the circuit circumnavigates this problem nicely.
This thread in some form or another is also very popular on other forums.
Does this indicate that anyone who flies a wide circuit per definition does not sub to any of these forums or are we all 'guilty' of flying a wider circuit than we think!
I have certainly flown with folk who are self proclaimed 'tighters' and thought that they were flying wider than I would have done.
Have fun
FD