I find Paddle crab to be a significantly better bait for Rig then prawn. But when paddle is not available it is the next best option. At times they would take prawn and leave the crab baits untouched, the other night HLS out-fished me using prawn when I had paddle crab.
Prawn is also a usful bait to have on hand when chasing Moki. Both raw and cooked prawn work on both species. Prawn and Crab are excellent when the doggies are around because they do ignore them, Red Cod also rarely take them so they are a good selective bait.