Thought I'd chime in. I've had an Herbalaire for about four years and an Extreme for about two, and a Volcano for about four (among others.) The Herbalaire just plain beats the Volcano. For me it's because I can fire up the Herbalaire in about two minutes and medicate. I don't use bags with it--I like the teflon.
The only thing is the crucible heats up and cooks the herb if you leave it in, so I pull it out (I use the scissors from a sewing kit, in a pulling instead of squeezing action to lift out the hot crucible. That's literally my only complaint though. I slightly prefer the flavor from the Extreme, but it's not nearly as fast, easy or efficient. I feel it doesn't work well at all unless it warms up for at least 30 minutes.
I've got several other vaporizers, but I don't use any of them.
If I had to add up all the pros and cons, the Herbalaire is the best. If I bought one for someone else, it's the one I'd buy. The only thing I'd do to improve it is design a ceramic crucible, which wouldn't super-heat like the aluminum.
Oh, and...I'm thinking of adding a pen to my collection, because I might USE it now that Colorado's a somewhat free state. Thing is I provide my own medicine and figure I'll have to make earwax, and don't know anything about any of that.