If you like this, I recommend Breed77 and Flametal. Flametal is more on the side of instrumental prog metal while Breed77 is alternatvie metal with vocals, and they both have flamenco parts in their tracks.
Duality_Nation, Zipaks: ... No, sorry. I'm from Spain (and there are some guitarist here, you know) but R&G are the first that I listen so original. Perhaps the more close to them, and spanish, is Paco de Lucía. But R&G sound different, really modern and they're unique, technically and creatively speaking. These are my two cents, perhaps I'm wrong.
Hmm, the similar artists aren't really the same sort of thing, theres a lot of spanish guitar stuff in there, but it completely lacks the percussion that the slapping of the guitar casing brings.
Does anyone know of other artists who are more similar to RyG's style?