I love this paper
The only item of note is that this paper does not have a perforation to make it easier to pull the paper from the notebook. This is normal for this type of notebook, but, when I purchased it, I wondered if it would have the perforations so I figured I would mention it.
I decided to test this by becoming increasingly more abusive to the paper. I started using five different fountain pens with nibs ranging from EF to M and I used Waterman brown, Noodler's black, a custom gray / green, and private reserve inks. In every case, the writing was crisp with no bleed through. So far so good...
I pulled out some Pilot Parallel pens. For the record, this ink is awful in that it really likes to bleed through paper and they write very wet. With the 3.8mm pen.
This paper is excellent for fountain pens. In all cases, writing was crisp (no feathering) and no bleed-through.