I agree with Dave. I have some computers with dual boot knoppix/debian but I still keep knoppix as 'default', and at this time don't seems to me knoppix is causing more issues than debian itself. I think the best hint a knoppixer can give to 'newcomers' isn't "don't install it but don't apt-get upgrade it.
I've tried others distros which are better than knoppix in some aspects such ubuntu that recognize my printer on the fly, or kanotix that create automagically an usb_icon on my desktop when I put in a usbkey, but..."knoppix is rock, and well pre-configured for people that come with no many experience in linux!"