We have similar situation.
I'm also married and I have one kid, so I have to pay $6000+ AUD like you. And I'm from high risk country, too..
My occupation is financial investment advisor offshore 187 and I lodged my nomination 12/12/16 and I'm still waiting for results.
My MA told me that if I lodge my nomination and visa seperately, its gonna take 6-10 months for nomination and 3-6 months for visa.
If I lodge both together, its gonna take 10-14 months for everything depending on how lucky I am.
The processing speed is getting slower and slower. I don't wanna take that $6000 risk because two of my 187 friends actually failed the nomination.
Luckily, they only lodged their nomination so that they didn't lose that visa money.
For me, time is not an issue anymore because all the processing speed is so slow now. I just don't wanna waste any more money in vain.
Hope that my experience can help you making your decision.