I love the AS3 event model - it helps keep my code clean and lossely coupled. When I used to work on AS2 projects, my code was not so neat and classes were more reliant on one a
I would guess the best practice would be to use the EventDispatcher class where ever posible. You can read about it here:
http://help.adobe.com/en_US/AS2LCR/Flash_10.0/help.html?content=00002325.html
The UI components also have very AS3-like event dispatching.