I am thinking of taking the plunge and using some of my free disk space to do a LFS build.

Should be interesting.

OK? Good luck?

Don't worry, if you use Slackware and Gentoo you won't have any problems at all. Just try to learn as much as possible from each stage. First time I did it I just rattled through it, following the instructions carefully but not doing much/any background reading, and I ended up with very little new knowledge.

I think it is definitely worth going through at least once in your life.

I'm currently in the process of building my first LFS system and am learning a lot. I'm doing it to learn, but in the end I also want a maintainable (e.g. package management) system. Therefore I am implementing the user based package management scheme, which is powerful yet simple (both conceptually as well as without requiring anything beyond what is part of the base Linux system) which is described here.

LQ user Lufbery also has a nice, up to date (LFS 6.6) writeup/Build notes for the process that is worth a look if you're curious here.