Several days ago,the r4i gold team has released r4igold 3DS flashcard to support 3DS handheld,yet at the same time,the offical also announced that this card was only for 3DS console and can't use on other models,because the 3DS cart's encrypiton part is different from that of a NDSL cart,so if you put this card into DSi console, th NDSi will show" no cart inserted".
While,today,i got a r4igold 3DS Flashcard and made a test on both 3DS console and DSi console and found it works well and didn't meet any abnormal things.Here is a video show
about this test :
Source :
R4i ds site
3DS Flashcard