Interesting point, I was going on the fact that I keep a lot of mechanical engineering books for the tables in the back of various material properties, and having a kindle instead of a 6 testbooks would be physically so much smaller on my bookshelf, but for actual content the kindle might not be the best choice.
It's probably best as an additional copy of a reference work. Maybe read it straight through the first time on the kindle, but have a paper copy around for more typical reference use. You'd still have the kindle copy handy for things where you're mobile and need to dive in for a quick search.
