I thought i'd give this a try as my hands can be a touch shakey at times, at more than a few times using the Stedi applicator that comes with the panel liner i've made a bit of a mess trying to get into small panel lines.
This has been pretty helpful, it flows well and can get into small lines and sometimes without leaving anything to clean up.
It does take some getting used to, as much as you dont think you should, fill the well on the pen all the way up to the breather hole, NOT the tiny holy.
The panel liner flows a lot easier on its own then, otherwise you do have to put some pressure on the nib.
Also found this very useful for kits i didnt really want to scribe. The tip can be pushed into edges and just glide along panel lines and where parts meet to add a new panel line, and can be very helpful for shallow panel lines when you dont want to bust out the scribes.
Great tool to have in the arsenal.