I think tohd is great, but fromhd is even better. After you've booted the first time using:

knoppix tohd=hda1

you can skip the lengthy copy process on subsequent boots by using:

knoppix fromhd=hda1

Knoppix comes up quickly with this cheatcode (I was fairly startled the first time I tried it). I think the fast boot time may give this configuration the edge over toram.

I'm still using the Knoppix CD to start the computer, but I can eject it as soon as the hard disk takes over. Now I only need one CD-ROM drive!