Don't know exactly how to answer, but I guess I'd go "Yes".
I'm not really into signatures, per se, but I do have two signed books -- both of them because I helped edit them (no, not WotC or anything). Collecting signatures doesn't really do anything for me except in these cases.
OTOH, I DON'T like to keep my books clean. Like my school books, I keep all sorts of notes, running arguments, highlights, and the like. These are not novels -they are rules, and rules need commentary. I am the Master of Marginalia - ask anyone who's seen my copy of Maleficium (old White Wolf supplement for Ars Magica) to know the level of notes and arguments carried on in my books!