The HP Dev One follows the HP EliteBook's poor design of pairing the pointing stick with 2 mouse buttons instead of 3. Without the middle mouse button, you can't scroll with the pointing stick and you'll need to use the trackpad (or apply some hack to the 2 available buttons), which makes the pointing stick a less effective tool.
I've tried that, and it was so uncomfortable to hold down both mouse buttons with one thumb that I did not find this workaround worthwhile. It was awkward using both thumbs to do the same.
