The C130 system is a very good one. It can take 20 tonnes of water. Set up time several hours. Needs about 500lb of permanent fittings in the aircraft - unnoticeable except for weight in normal military operations.
It was proposed widely in Australia several years back. I contributed to that proposal. Phil Koperberg did not like it. At the time he was only reluctantly using aerial methods.
The C130 is not, on its own, a complete answer to the types of fire we have on the east coast of Australia. It still needs helicopters for close support. But the C130 outperforms the Canadair 215 and 415 in this geographical area.
I have not modelled the Skycrane against the C130, but I suspect that the Skycrane will outperform the C130 in the area around Sydney. Given strategically placed dams or ponds where it can pick up water, the Skycrane will outclass the C130 in one key area - turnaround. This more than compensates for its reduced capacity.
ET