If I were you, I'd check out the Herbalaire. (herbalAire - Smokeless Herbal Vaporizer)
It gives you the option to use a direct draw system or use the bag system. There is proof that the Herbalaire can take the used up or spent herbs from the Volcano and still get vapors from it. I own one and could not be any happier. I have tried the "whip style" vaporizers but they don't work anywhere near as good as the Herbalaire.