If it works as the Wii firmware (and it probably does, because of the similarities between the two NUS servers), a ticket is installed in the flash, and even if you copy your DSiWare app on the SD card, the ticket stays in the DSi and is verified.
I wanna grab a 360 Slim and a 360 E one of these days. Missed the boat of getting them at their lowest though, once they were discontinued. Could've got them for cheap back when I was a broke 20 something working at Target, but then again, I was a broke 20 something working at Target