How well do the pages hold up over time? When I look back at my notebooks from ten and twenty years ago, the pencil has not held up well. I think the rubbing of the pages from use and moving them around has really lightened the marks.
My journals are net yet that old, 3 to 4 years, so probably too early to say. Thus far, they look good, and with a really dark pencil, even with a bit of fading it doesn't really matter.
For anything I'm going to keep, I use ink now.