I just picked one of these up at the seattle shop. I threw some Soul Tip paint in it and it rocks pretty good. You gotta wear the nib down a bit to really get it flowing but after that it's great. Its a clean marker too, no leaks and super easy to refill (hit it from the hackable). I've used it for slaps too, it's the perfect size. Buy one and give it a spin you won't regret it!
I run this stuff through my brush tipped marker for slaps. It goes on thick and seems to run good in the Seattle weather. IMO it's worth the money [for now]. Also you can put this ink in pretty much any marker and it will run like a champ. I've even soaked sharpie tampons in it.
This stuff stains hard and it leaves behind this yellowish ghost. I just wish it was cheaper so I could run it through mops again. I use this stuff primarily for slaps and my 15mm marker. If AP dropped the price they could corner the American market.