I grew up abroad (in South Africa) and I would go like a shot. But there are a lot of things you should take into consideration (speaking as the child of parents who chose to move abroad, so I didn't have a choice):
Firstly, how will you feel leaving your family and friends? I don't actually think that how your family feel should be a consideration, because you have to do what works for you and your immediate family, so you shouldn't stay because your mum will be upset, but you should rather consider the impact on how you feel about leaving your mum, rather than the other way around iyswim. Also you need to consider the impact that leaving your family will have on your dc, and the impact it will have on their relationship with their extended family, because it will have an impact. When I lived abroad we didn't have such inventions as skype, and phone calls were prohibitively expensive, but even now with skype and phone calls, they are not a substitute for a real relationship with extended family.
I first moved abroad when I was six weeks old, returned when I was nearly five, and so essentially I met my extended family for the first time then. We moved back when I was nine, and by the time we came back, I was nearly twenty, and tbh I had no relationship with them at all. Yes they are aunts and uncles and such, but in truth they're just people, there isn't that auntie/niece/cousin relationship because it never developed. Even if we'd had skype it would never develop - they're just people on the other end of a computer really. I think as a parent it's easy to think that you're maintaining the relationship, but as a child I can tell you that it's not the same. (although obviously I am referring to a more long-term stay, although two years in the life of a one year old is a long time).
In terms of regular visits, I think you need to think more along the lines of that these are not really realistic. Because although you may intend to go home every six months, or intend to fly family out every six months, in truth things happen and money is needed elsewhere, and, if you're honest, once the novelty of having a family member living in Australia wears off people aren't going to want to spend all their holidays visiting you, they have other commitments and other things they want to be doing with their holiday. So while the hope is obviously that you will be able to see people regularly, you need to go in with your eyes open to the fact it's unlikely to happen like that in the long term.
And if you're leaving your friends behind it will be impossible to just come back and slot back into your old life. People move on, if you're living in different countries then your thoughts and ideas change, and when you come back you suddenly realize you no longer have anything in common with the people you left behind.
I'm not trying to put you off, I would move to Australia because the lifestyle is very similar to that in SA (but without the political and security issues in SA), and because I am aware of the potential pitfalls it's not something I would be too bothered about. But having known lots of people who have emigrated abroad it can come as a massive shock to suddenly realize that you haven't seen your family for three years and they're not actually that keen to come over because they have other things to do, and you can't afford to go back because you don't have the money, iyswim.
Also, if you commit for two years then what? You'll be giving up jobs here, are you prepared to quit your new jobs abroad, fly home and have nothing to fall back on? It's not easy getting a job at the moment - there are no guarantees on that score.
Personally I wouldn't put a time frame on it because I think that will apply a huge amount of pressure on both sides. Either you're committed to giving this a go and seeing what happens, with the proviso that you'll communicate how you both feel, or you're not. I think the need to put a timescale on it shows that actually, this isn't what you want. And if it isn't what you want, then it's a long way to go to find out.