I kinda assumed that most developers took a similar approach to me. Laptop because portable when you need it, hooked to large screens, nice keyboard, nice mouse/whatever. I don't know what having a desktop would really buy me. I do 99% of my work with the laptop docked but that remaining 1% it sure is handy to grab it and go.
If you are just making web apps, it does not matter, but I do data processing where having the headroom can make a big difference.