One of my absolute favorite markers. Perfect size to fit in your pocket or discreetly in a bag. I carry this and a meanstreak with me basically everywhere.
I've been using AP black marsh with OTR blue ball pen fluid in this and it crushes. Flows through the nib beautifully crisp or flared out and because it depresses further than the PX30, you can rock some drippy chisel tags if you want. I'd rate this six out of five if I could.