well in my limited time i have only used T.D.Waterhouse and yes buy/sell online i have had no problems untill tonight, you can obviously do preview orders and refresh and sell or buy when your happy with the price..
well i have been looking at SEY and the current T/O but i tried to buy in at 16.15 today and waterhouse wouldnt work properly the trades of buys to sells is massive so will look first thing in the morning but im guessing i missed the boat as i can see it going manic tomorrow first thing but if it opens low i will be buying in..