My sister and her DH were in a similar situation except for Oz.
They took it, the company paid for their relocation costs and helped find them schools and a house.
Neither of them had ever been to Oz, their reasons for going were due mainly to negative push factors in the UK as much as positive knowledge on Oz.
It worked well, they've been there ten years+ now, are full citizens and the kids are young adults with great opportunities ahead. They uprooted their children much older (end of primary school) which I think is harder.
They have a similar housing problem to uk though of first time buyers struggling to get on the ladder... So is not Eutopia and the country has it's issues.
It worked as
- they both wanted to go due to bad work opportunities here and poor work life balance,
- they were both committed to give it a go.
- They had a plan for return if it didn't work out.
- They didn't have rose coloured glasses on and expect it to be perfect, it was stressful at times and leaving family was hard - they expected that.
I think in your case, given you don't feel so keen you could go on the condition that it was a trial, so you agree to give it 2/3/4 years, treat it as an adventure and have an exit plan and a place to come back to.
But my biggest concern in your shoes would be that the conversation doesn't seem to be balanced with both sides being heard. You both need to discuss is realistically and not shut down doubts or concerns, but explore them constructively. If he is normally respectful of your pov you could help from your side by sorting him you are at least willing to consider it properly and not just dismiss out of hand, because if it doesn't happen you don't want a while ton of what if's laid at your door for years to come.
My sister rented her house out for a while back in the UK and it was only sold once they were happy they didn't intend to come home (a few years). As it was, if they had come home it would have done no harm to their lives and would have just been an interesting thing on their CV.