Kyle Rankin, author of Knoppix hacks back in 2008 wrote an article in Linux Journal http://www.linuxjournal.com/article/10075 which has become even more actual with 6.X.
The essence is, you can now obtain most of what you get with a remastering just by tweaking initialization parameters (up to, and including, tweak of initrd), using the persistent image for just about everything you need to make Knoppix work like an ordinary distro. (Nobody with some basic Linux skills really has a good reason to complain about missing packages on the CD/DVD anymore.) There is a small article about Rankin's advice on the wiki, but I wanted to post it here.

What has become a bit of an issue with the new possibilities, is the FAT32 4GB filesize limit effectively limiting the persistent image. This should not be regarded a serious limitation for data, for databases etc can just be stored on other file systems - it's about what can be installed/upgraded.

If we could easily add another 4GB persistent image, it would be nice. Anybody having experience with this?