The first thing I noticed is that they redesigned the pump valve cap, making it easier to add your ink or paint. The valve doesn’t have to be pried off with a sharp knife any more. It just pulls out by hand. The spring is also contained in the valve, and won’t accidentally fly off. Much better.
The ink I’m using is Higgins Black Magic India Ink. I dropped about a teaspoon into a one ounce plastic jar, and filled it up with water until I got the medium gray value that I wanted. I used a syringe to load the marker body with the ink, and reassembled the marker.
It marks really well. I can carry this around with me for sketching now. I barely used any of the ink I mixed up, so that should last for quite awhile. I have six other markers that I can fill with undiluted ink, different types of ink, or thinned paints.