Using RawkSD on a 4.2 Wii, no problems... 195 imports on a 4GB Transcend 133x (various RB1, AC/DC, GHWT, GH5). I've even managed to migrate a couple of the songs, mix them with my legit DLC without messing up the file ordering/numbering on the purely import card.
Waiting patiently for RawkSD...