I personally think that Australia shouldn't be trying too hard in finding a new Warne. Casson, the last time I saw his stats, averaged in the 40's with the ball I think, and he gets a test call! I think they're being a tad bit too desperate here.
They should just back their strength's and go with a four-pronged seam attack. Symonds and Clarke can do the job if they want to slow things down.
He can bat, MacGill can't. Casson made a ton and picked up a 5 for in the Pura Cup final IIRC.