I actually used default keys in the BF3 Alpha and Beta, and boy, it was a pita. Now in the final release I use the numpad and it is just so much better, but yeah, some things are just hard to get working.
As demalion mentioned, Mirror's Edge was the first game I found that couldnt actually bind numpad-enter, which made me look for a solution. The first lazy solution was to download the AutoHotkey and run a script to rebind. That said, the AutoHotkey util is great. Not only can you rebind buttons or implement macros, you can also do it context dependent so if you alt-tab out, it disregards all bindings, switch bidningds dependon app, etc.
After a while I for some reason remembered the config-files and edited them directly as a solution. Beyond Mirror's Edge, the same problem was also in the new Deus Ex:HR, where you had to go in and bind the ascii-value for numpad enter if you wanted to be able to use it. People in the Deus Ex foras was glad for that a solution to that problem. What's weird is that it had to be crowd sourced instead of the game-maker just saying how to do it.