Can't recommend Nabtrade enough. Cheaper than commsec, Iress free after 5 trades, hasn't been offline since I've used them, if there's a delay in processing on their end, they'll take responsibility and will reimburse you the loss (you just need to ring up and request it, I had a screenshot but don't think it was needed).
I believe the only difference to commsec is you can't enter a manual centre-point trade, but they'll perform the cp trade if available. Also chix data is disabled by default, email support and they'll enable it on your account once you have IRESS.
