Ann: G Medical seeks delisting to pursue Q4 NASDAQ listing, page-604

So my thoughts on the reason for delisting is that the company can restructure at will and provide better options and more 'mystery'. If the company stays on the ASX and is doing badly (a large amount of negative sentiment has been tossed around recently) then the price on open to USA will be relative to the ASX price. If they separate from the listing price new investors are likely to be more upbeat and interested in investing in a 'new' company and a new market.

Could be many other reasons too, including reasons that would make the management more money but if they make money and I make money that's ok