Of course running stuff from harddrive is alot faster than dvd, how can you say its not?
Because I don't know the ratio of auto-detection time and the actual bottle-neck of DVD booting. I haven't tested the feature and I didn't want to download Knoppix just to know it. Thanks for your answer.

I suggest adding my approach of an read-write functionality when booting from an ISO-file. I would really like that.
if knoppix already does this though cant we just load a sabayon iso with a knoppix disk?
No regrettably not. As long as the Kernel is different in Knoppix and Sabayon, what it surely is, you cannot load a Knoppix Kernel and load Sabayon modules later on. Sabayon is configured to work with the Sabayon Kernel setup.
But what about a maximum ISO-file, which can be mounted read-write? Squashfs is read only, as far as I know, but we could add a loop file at least for the home directory, which is mounted when booting from a ISO-file. Can we write in a fix-sized file inside an UDF-filesystem? We could than use a Sabayon setup even without install...
Do you like that idea? What problems may we have to deal with?
Cheers,
whilo