One thing I found that I really liked with Canson Heritage watercolor paper was the way a wide range of pens worked beautifully on its surface. (I was testing the hot press surface.)
In this portrait I used a fountain pen filled with Platinum Carbon Black and two Sakura Pigma Professional brush pens with solid fiber tips. (An FB and MB.)
If this paper were less expensive I would buy it just to do sketch studies with these pens. But unfortunately I live in the real world where that would be a rather expensive habit to encourage.
I can see myself buying a block once a year to have a little binge.
Note: The really light lines you see in the portrait are ink lines from the Sakura FB that is very dry and running out of ink. It gets almost a graphite-like quality when it’s at this stage. I hold on to the older pens for a long time as it is fun to start drawings with them.