So I finally caved and bought it. After sitting in my Amazon cart for most of the year, last week I pulled the trigger and ordered the Lamy 2000 Multi Pen (which Lamy refers to as the 4-Color Ballpoint), and this is another of those purchases where I'm kicking myself for waiting as long as I did. This is hands-down the best multi pen I have ever used.
Fit and Finish
No surprises here. This pen is pure Lamy 2000, from the brushed Makrolon finish to the stainless steel spring-loaded clip and knock. It resembles a slightly girthier Lamy 2000 ballpoint pen, and I've found that the added width makes it more comfortable to hold for longer periods of time. This pen looks stunning in a three-pen holster along with my Lamy 2000 fountain pen and ballpoint. I'm tempted to finish out the set by picking up the rollerball and the .5mm mechanical pencil, especially since I've read that the rollerball can be hacked to take a wide variety of common refills, including Montblanc fineliner and Pilot G2 refills.
Gravity-Driven Color Changing Mechanism
By far the coolest thing about this pen is how you switch between the different colors. At the back of the pen, around the knock, there is a series of colored panels in blue, red, and green. To change colors, you rotate the pen so that the color you wish to use is facing you ("black" is the clip), then press the knock. Once you're finished, press the knock again to retract the refill, rotate to select a new color, and repeat. It's mind-bogglingly simple to use, and it baffles me how Lamy can come up with this idea and execute it in such a way that the mechanism works perfectly nearly every time.
One note: while you can use any color refill in your Lamy 2000 Multi Pen, the color references will always show black, blue, red, and green. There's no way to change the colors on the body of the pen itself, BUT many D1 refills also have a splash of color around the tip for reference purposes. If you venture outside the black-blue-green-red range of colors, it might otherwise be easy to forget what you have in the pen.
The big downside to D1 refills is that they are small and therefore don't last very long, especially the gel versions. (Zebra Sharbo X gel refills are excellent, but they can get very expensive very fast if you're using your multi pen for more than quick notes here and there.) To get more mileage out of your refills, I'd recommend sticking to ballpoint or hybrid ballpoint refills. Based on what I've used so far, I'm most impressed with the Uniball Jetstream D1 in .5mm. I have these loaded into the blue and red slots in my Lamy.
In terms of standard ballpoint refills, the stock Lamy refills are fine, but they can be a bit light in certain colors, especially the red and the green. I purchased a couple packs of the Monteverde Softroll D1 refills in blue-black and orange, since I'm generally a fan of Monteverde ballpoints. The blue-black is nice, and I currently have it loaded in the "black" slot, but the orange looks gross (brownish in color and way too light to be usable). I have a pack of the Schmidt D1 refills on the way, so we'll see how they turn out. I'm a huge fan of Schmidt's Easyflow 9000 and the D1 version has received good reviews.
For a complete discussion of the various D1 refill options, I highly recommend that you visit Ana's Epic Refill Guide over at the Well-Appointed Desk. It's comprehensive and will give you a good idea of what's out there. In my experience, JetPens and Amazon typically have the widest selection of D1 refills.
Takeaways/Where to Buy
I consider the Lamy 2000 4 Color Ballpoint to be the gold standard of multi pens. It's well-built, reasonably priced, and takes a readily available refill style that's not proprietary. Given the small size of the refills, they can be expensive to own as your primary writing instrument if you plan on using them for something like journaling or writing extensively in longhand, but I've always appreciated multi pens as annotation and note taking tools.
The Lamy 2000 4 Multi Pen can be somewhat difficult to find from traditional pen retailers, because it's a bit of a niche product. I purchased this one via Amazon. If you're interested in checking out the design and feel of the Lamy 2000 but don't want to shell out $120+ for the fountain pen, the Multi Pen and Ballpoint are good places to start.
Disclaimer: I purchased this pen with my own funds for my own collection. This post contains affiliate links.