Sgstair and me are planning to develop an application which should show you the differences between a nds-emulator and nds-hardware. It's main aim is to raise the compatibility of emulators. If developers can easily see the differences and test the accuracy, the compatibility may raise a bit. We still could need some help for it. So please check the page out and contact Sgstair or me, if you think you could help us for any of these listed tasks (have a look at the link below).
-Thanx
http://wiki.akkit.org/Nds_test_apps