I'm only interested in things that are at least as close to pure Debian as Knoppix. Therefore, I may be a bit too skeptical about Mint, being, essentially, an Ubuntu derivative.
While KK himself has not been interested in making a pure-64 Knoppix so far, he has in no way been negative towards such attempts, and as you well know, current Knoppix is, actually, a hybrid system if you use the 64-bits kernel (which I do as much as possible).
And as soon as we have a package like knxbootstrap working, there will be far less extra effort needed to make a Knoppix-type adaption.
Last time I looked into it, 3 years ago, it looked like Knoppix was way ahead of Debian Live in most respects. Hopefully, they have closed som of that gap now.