I have to say that for me the fact my 2-years-ago widowed mother here in the UK is the perfect excuse for not even being able to ENTERTAIN the idea of going back to Oz in the foreseeable future! She's great in that she always says 'Don't whatever you do stay in the UK purely on MY account! Do what's right for your family'. Admittedly she did go to Tanzania for 8 years in her late 20s so does KNOW about leaving parents behind. But she's a huge part of my DSs lives, doing 2 school runs a week, dinner on Sunday etc.
DH's parents died in Oz 9 years ago (and I can safely say there's no WAY they'd've supported this move if they were still alive, DH would never have been spoken to again, and I'm serious! His 55 yr old single brother can barely tolerate the betrayal even now...).
I reckon it's always the hardest on 'the first generation'. If you stay in your chosen country, though it will possibly never feel like 'home' to you, your young DCs will never know any different- they will grow up there, be educated there, have friends and eventually spouses there. Many ex-pats use that 'off our hands' time to emigrate back to Blighty, but I believe never settle back here as the family is still 'over there' and- a fact I too have come to realise, blood is FAR thicker than water! You'll be 'torn' forever. Unless you bring the entire family along and even that has its pitfalls: 'Mum and Dad', knowing no one, emigrate to be near you. You have to spend a lot of time helping them integrate- being there with them really, THEN DH's job relocates to another capital city- bearing in mind in Oz we're talking possibly a thousand miles away- then Mum and Dad are left high and dry, adrift in a foreign country, unable to afford to either move again or go home, just because they wanted to be near you and the DGCs.
The 'solution' is to be very wealthy. I knew a few Pommie women who had NO trouble with homesickness/ missing the family, because they flew back to the UK at least twice a year with all the DCs in tow!
One issue- I'd never uproot a DC over the age of 12, max, unless I had no option! By then, they kind of know who they are, they have proper friends, they have an identity culturally intertwined with where they have grown up. I met several 'Aussies' whose families emigrated there when the DCs were teenagers and they have a double whammy of the parents still yearning for 'home' AND adult children who still feel a bit out of place amongst their Australian peers having not had that vital teenage socialisation in Australia, yet not being 'English' either.
Oz is different in that the population are a lot less mobile than in the UK. Many, many DCs live at home whilst they attend the local university. They remain close to school friends. Every social group you get into has a loose connection with a school, university, or family. They all party hard in their 20s, maybe doing their Overseas Experience for a year, but they all end up marrying each other, then, in the instance of Brisbane, straight back into the arms of the Catholic church, 3 or 4 kids, all off to Catholic school, doing weekend BBQs with the same folk they've known since they were at least 12- who are all now married with DCs in Catholic schools! It's hard to feel a part of that!