Why the R4? It's OUTDATED since 2 years ago. The newer flashcarts have much more support for latest homebrew, including DSi compatibility, Xvid/DivX video playback, GBA Emulation (GBA is considered dead, legal or no?), etc.
The new SuperCard DS Two is a winner in my book (I have the AK2i; not that 2.0/2.1 stuff).