Yeesh dudes I've bought 100% of my 3DS via DD after NSMB2. On a handheld it's totally the way to go. The only time you'd ever possibly end up hosed by the account system is if you actually lose your 3DS somewhere. They're fine about letting you redownload if your system breaks and you send it in to them.
I love having no options in how I choose to handle my broken hardware.