Read this for the claim about knoppix needing at least 1 GB of memory :-

http://www.finnix.org/Frequently_Ask...and_Knoppix.3F

While at it, I am still very uncertain if the claim made of finnix auther is true. Nevertheless I found that knoppix 6.2 mounted a 1G tmpfs, but the tmpfs is only used if there is no persistent store. When using persistent store, the tmpfs is not used, but it's remained mounted.