I run into the 8GB limit on my laptop pretty regularly. Mostly due to VMs for testing and building for other systems. But I also recently found that running Android Studio, plus the emulator, plus my usual stuff pretty much shuts my machine down. I had to use a VT to kill my mail client, the VMs, and some other processes, in order to get the mouse and keyboard responding in X again. Java memory usage is kinda crazy.
This is my use case for having 16GB on my laptop as well. Being able to simulate the network architecture of our infrastructure with a bunch of little 512MB-1GB VMs is a nice thing to be able to do.
If I'm not doing development with a cluster of VMs though, I rarely go over 8GB.
