I use IB now, the rates are very low, was using Macquarie and paying a flat US$10 per side plus GST, but when the broker I was using left they put the rates up to US$17-50 plus GST per side, was happy to pay more for Macquarie but hiking the rate 75% was too much, didn’t look elsewhere as I already had an account with IB.
Only downside with IB is you have to be on hand to place, amend and cancel orders plus any f@ck ups are your responsibility, trust me you will get no joy from IB.
There rates are here.
https://www.interactivebrokers.com/en/index.php?f=commission&p=futures
As to other brokers I think those you listed are about it in Australia at present and a few of those are third party and use IB anyway, unfortunately these days the number of futures brokers has diminished, think there are not as many private clients as there used to be, Forex and CFD,s seem to have taken a lot of business, personally I think futures are a far more even playing field but contract size is maybe the biggest issue for new traders were as the likes of forex you choose your own size.
As to any lag in data with IB, seems fine to me but I really wouldn’t know anyway but my orders almost always get filled at the price I have set or is showing in the TWS be they stop, limit or at Market, same with margin, I have never had an issue but then again I don’t load up or add to positions.