The Volcano does a great job of filling a bag, as does the much cheaper herbalAire and Extreme. Bagged vapor is always diluted to some degree, and isn't going to be quite as fresh. The Cloud provides big, direct hits and gives the user control over the size and density of them. They're very different designs.
I used a bag filler (herbalAire) for quite a while, but found that I tended to load a lot and use a lot. You can do that with the Cloud as well, but you can also take one hit, find that you don't need any more right then, and shut it off. Once you fill a bag you're committed to inhale it all or waste it.
If reliability is of great importance to you, the Volcano is a time tested design, but so is the herbalAire and the Extreme, so if wanted bag use I'd go for one of those. They also offer direct draw and provide all the hardware for both vaping methods. The Cloud was designed for the vapor connoisseur, so if you think you'd like big, clean, water filtered hits, it's hard to beat for performance. If I were you though, I'd preorder the new EVO- get the newest version and save some $ as well. You will have to wait a while for delivery though.