Interesting view on vacations. I had not realized vacations are vestiges of the banking system. Though I somewhat agree with the article about other developers being able to dive into your code (what my co-founder calls the Truck-Test : can someone take over your code if you came under a truck?), I feel that you definitely should take some time off from your daily work in order to get a zoomed out perspective on your work and get to meet people outside of your organisation.
This really helps you get an overview on how you are doing things, whats happening in the tech world, and most importantly INTERACT with the outside world. We as developers tend to cozy up to our dev environments (physical as well, not just virtual).
It also helps you catch up on new technology and better your workflow and of others'.
Go ahead, take your vacation!