The GAIA Mk II - one of the major issues for water is when it reaches the lower levels, around Lake Eyre
(before they change the name to suit ten Aboriginals - insult to the bruvvas, that name!)
has a huge quantity of salt underground, and thus salinity would (gasps) rise to prominence in any discussion.
Without open access to the sea and constant tidal renewal, the Eyre Inland Sea would become a new Dead Sea, and the yellow and red tailed frog-jumper
(or whatever it is the conservationist extremists claim)
would become extinct due to crashing into the salt covered surface
(not to mention the Crested Gullywhumper once thought extinct but newly re-discovered in the Lake Eyre Basin)
As it is, a hell of a lot of water flows inland during The Wet and is absorbed by the 'lend' (bro) or is evaporated... so my view is an opening to the sea AND water diversion
(wonder how many bodies in barrels they'll dig up in SA?)
Many will project disaster - I say those are pure guesswork.... and the results will probably be fabulous.