Currently there are a few different r4i sdhc 3ds flashcarts in the market, both of them can work on the 3ds xl and other ds consoles. but what is the difference between them, and which one is better, you may feel confused about them, this post will tell which one is better, r4i sdhc dual core or r4i sdhc 3ds.
both the r4i sdhc dual core and r4i sdhc 3ds are working great on the latest 3ds latest firmware V6.2.0-12 and dsi latest firmware V1.45. if you buy the preflashed r4i sdhc dual core or r4i sdhc 3ds card, you can just use the latest firmware from the official site and then they can work on the latest 3ds and dsi console.
For the features, both of them can play ds games and can play most ds games. they have good game compatibility. for other deatures, they don't have too many extra features, but they can run homebrews well.
I would recommend the r4i sdhc 3ds card more because this card has a better kernel and has the old history. more importantly, everytime when a new 3ds firmware comes out, the r4i sdhc 3ds released the update patch or new firmware quicker then r4i sdhc dual core. this means r4i sdhc 3ds card can work on the latest 3ds firmware quicker.