Binningup does get the sou westers and can be fun when there's swell, but you need heaps of swell. No swell and its a bit boring gets pretty choppy. If you go south to australind you can find some nice flat water. only 15 - 20 mins away.
I had a cracking kite there on Monday. Even though the swell was smallish in Perth, there was an occasional nice little wave coming off a reef just to the north of the life saving club, which is surprising as it is where the guys go when the swell is big.
There is also quite a nice left that sometimes works to the south of the life saving club, but at certain times of the year it has heaps of pinnacles that are very shallow, but other times of the year they are covered with sand. I would recommend a swim out there first unless you have spare fins.