Today R4i SDHC official team released the update patch for their R4i sdhc card,after you update the card, you can make it work on DSi firmware V1.4.1, let's take a look.
Here is their news :
IMPORTANT: R4i-sdhc has broken NDSi V1.4.2 sucessfully! Meanwhile, The updating patch for NDSi V1.4.2 has been released! Can V1.4.1 products in perfect upgrades.
You can download the update patch from here : R4i sdhc update
Until now, most of the cards hace released the update for V1.4.2,such as R4i gold 3DS, DSTwo, iSmart mm, iPlayer, R4i SDHC .....AK2i also released the update video, but haven't released the update patch ,but seems it will comr soon!
Here is the update method for you
How to update your R4i SDHC to DSi firmware V1.4.2