I use this card for Autodesk Maya. I finally upgraded from my old Quadro 600 that worked good, but was looking for more performance. This card delivers. It's definitely pricier than consumer cards, but works well when you use 3D design programs or even Photoshop. I don't own a Quadro 4000, but looking at the specs, the K2000 is similar with more CUDA cores at half the price (win-win).
So far the only down side is early driver issues. 30 bit color no longer works in Maya, and the Force 10-bit mode in the driver causes both Photoshop and Maya to crash. That's very disappointing, since that's why I wanted a card with two displayport outputs to drive my 30 bit enabled primary monitor and displayport only second monitor.
However, like I've seen with the 600, drivers are updated frequently by NVidia, so I'm confident they'll get support up and running especially with their certified drivers.
Unless you need the extra performance or two displayport outputs, the K600 can be had at less than half the cost and still has good performance, making it a better value in my opinión.