i have the current R4 and i almost threw it away to buy an acekard until wood came out and how confident are you that wood will be on this r4 3ds and wood doesn't work on clones that's why i'm concerned if these are clones or not.
The R4ids.cn 3DS card uses a patched version of Wood R4 that is created by the R4ids.cn team with help from YWG. Visit the website and you will see it. It may also be the only one of these three that could be patchable if it is blocked when Nintendo update the 3DS firmware.
Personally however I would recommend that you get an AceKard anyway as they are the best low cost flashcard on the market and have proven in the past that they are patchable to get around Nintendo's firmware updates.