I am now with Exetel (Optus network), 2 sims, 10$/1GB a month each. One sim uses 100..500mb max, barely any calls, the other one 800-900mb, sometime all of it, 150min of calls. The problem with this is that trafic not used on sim1 is wasted while sim2 could use some. Also, 11 or 12 months a year sim2 is using less than allowance so even rollover would help when 1gb is not enough.
So I looked at Belong. Same 20$ for 2 sims, rollover, sharing (which is called gifting there), all good except no international roaming which I want for internet banking when overseas (Aldi did not have it either but now they do, may be these folks change too?).
Aldi - the minimum is 15$ but there is roaming.
Is there anything else worth considering? Does anyone Optus-based do rollover or sharing? Amaysim does rollover in QLD (well, at least a friend of mine insists he has this) but not in ACT.
You don't need roaming to do banking from overseas just use a local som or wifi.
Aldi don't roam in all countries some they claim do, don't work.