well, it's not all machines that have Gb ethernet...ex G3's. thats one thing. another point is that it is possible to clone wout erasing your image. there's a brilliant donateware program out called carbon copy cloner (
www.bombich.com), where it is optional if you want to erase your disk before cloning over material/entire systems.
i set up a FW HD with different systems on different partitions, and then i just boot up from whichever image it is that i want to clone from, and clone the image to the appropriate drive.
hope this helps