Onyx pen has inbuilt Wacom digitizer which means it has very good pressure sensitivity. Pen nib is slightly harder, which adds to the paper feel. It is excellent, it makes it feel even more like writing on paper. Nib also does not wear out. However, Pen nib is short which means the tilting does not work so well as once you get past about 70 degrees, the pen nib is no longer in contact with surface, it is only the pen edges. If needed for anything tilt related, do not buy.
I would like to both thank the original poster for this recommendation and highly second it. Not being artistically inclined, I almost exclusively take notes on my tablet and I actually prefer the above stylus over the original remarkable for that. My source:
After using this stylus and noticing the wear on the nib (yes, it does eventually wear out), I started looking around for replacements, to no avail. But guess what? The reMarkable nibs fit perfectly. And so I have the best of both worlds: a pencil-like size and shape and a pencil-like nib. Very nice.