Dazza
Next time you see me down at Mullaloo come over and have a chat, I lived there for a few years and have a pretty good knowledge of the bays and kiteable spots.
I wasn't into kiting when I lived there and have only kited there a couple of times since but have done a lot of surfing and boating around the Island. As Ben said you have to take a bit of extra care as most of the bays are lined by reef, are full of line snagging moorings and there is some fairly heavy currents at certain places so if you stuff up and can't relaunch you can end up trashing your kite or worse still drifting out in to the open ocean. Basically your best bets are around near the Army Jetty/Natural Jetty/Bickley Bay or take a ride or catch a bus out to Salmon Bay. You can have a surf at chickens (near Little Salmon Bay) and then when the wind comes in kite in Salmon Bay proper. I wouldn't try to kite at Chickens, coz if you get caught inside, the reef is like razor blades.
Whilst it is possible to have a good kite session at Rotto it is definetly more of a place for surfing and it's often not worth the hassle of carting your kite gear around on a bike or bus but I'm sure you will find some good waves to surf.
Kent
Your bandit flying neighbour.
Striko's LAGO