I just received my Pilot Plumix and tried it out so I thought I would post a quick review.
First off it is a nice looking pen. I like the shape and the semi-translucent barrel. This lets you easily see how much ink you have left without having to take the pen apart…big advantage there over some other cheap calligraphy pens. The cap has two little fins on it that keep it from rolling away. These seem like a handy little addition, especially if you are using it on a drawing table or light box. On the other hand the cap is a screw on and I hate having to screw it on and off to use the pen. This could probably be fixed though with a fine file/sand paper and a little work to remove the threads so that it became a pull top. The cap does fit on the tail end of the pen and that is nice…it means I won’t have to spend forever hunting for it after having used the pen for a bit. The pen is very light as it almost completely made of plastic but it feels good in the hand and is comfortable to hold. It has two small indents for the thumb and index finger. I use a pretty standard grip while writing so these work well for me but they may cause issues for lefties and people that use different grips. All in all it is a good looking pen that sets well in the hand.
On to the writing. The nib seems to be a medium italic nib. The ink flows smoothly and it doesn’t seem to drag or catch as you write. The ink that came with it is kind of an anemic blue but it covers well and doesn’t bleed. There was a bit of show through on plain copy paper but not so bad that you couldn’t use both sides if you wanted. It uses Pilot Nakimi cartridges which can be difficult to find but it will also take the Pilot Parallel refills which are much easier to find and come in more colors. You can also use a converter like the Pilot CON-50 or CON-20 so you can use whatever ink you want. Others have just made sure the barrel is airtight (apparently some are and some aren’t but those that aren’t can be fixed with just a touch of epoxy) and just used an eyedropper for ink.
Overall for the price I think this is a great little pen. It does have some issues (no clip, screw cap, difficult to find refills) but in all it is a handy little pen for writing or simple calligraphy.