I always use pens. I write incredibly hard and I will break any pacer in the world. Pencils are just a pain in the ass to sharpen all the time.
I use pen for maths too.
That's my problem too =o
Like, some of my friends were fascinated by the fact that on each page of my note books you can feel dints in it from my writing.
I used pencil for chinese because every other character I'd make a mistake, and for drawing graphs, but apart from that pens all the way
Anyway, I've always been a fan of those cheapy 128p notebook things. The ones with swirly spines, after a month they get all deformed under my care =)