One thing that is for sure is that if you reside in Singapore, exercise employment in Singapore and are domiciled in Singapore then you WILL NOT be a 'Resident for Tax Purposes' in Australia.
Even if you don't qualify as a Tax Resident in Singapore due to the 183 day in country requirement (I think you will, but for the sake of the argument lets say that you don't) then the worst case is that you will be a Non-Resident for Tax Purposes where you will be taxed at a flat rate of 15% of your assesable income. Considerably better than in Australia.
If 'New AIPA' are concerned about the devil in the detail then they had better get cracking on it! It is already March, and the basing starts in June.
By all means, people in the firing line for this basing should satisfy themselves with professional advice regarding the taxation issue. I think you would find that it really is not as big an issue as some make it out to be.
Finally, wait and see how many Captains take up a voluntary basing in either Singapore or London. Why pay $100,000 of your hard earned to Honest Johnny when you could get away with paying about $30,000 to Lee and his mates. (Tax in G.B. is obviously more than in Singapore)