My friends 150 vapir seems conserve weed a lot better.
The Vapir One I take it? I've never heard anyone praise that one for efficiency. Just the opposite if anything.
My friends say a cano gets 4 people ripped of .1g where as the extreme is seems to take 5 times that.
Those 4 your friends are talking about must be Munchkins with no tolerance levels to get ripped on the equivalent of .025g. That's about the amount you get in the Purple-Days bowl, and while that much can get me high, I certainly wouldn't call it ripped.
From using the Extreme in manual mode (V-Tower), I wouldn't give it top marks in efficiency, but it wasn't bad either. I had no problem at all with overcooking. Are you using it in bag mode only? Not having used the Extreme as a bag vape, I can't speak for efficiency there, but as long as the air is in the correct temp range, and gets to all the herb in the bowl, it should be pretty efficient since your air flow and temp are constant.
I've used a herbalAire quite a bit over the last two years, and it's definitely the equal of the Volcano for efficiency. In fact, most people who have used both rate the herbalAire higher. Having a smaller bowl and using 18 tiny holes for hot air intake seems to make a difference. You don't even grind for the herbalAire-just plop a piece in the bowl. But even with the efficient herbie, I've felt like a good whip vape uses less to achieve the same result.
I'd rate my SSV as a little more efficient than I remember the V-Tower being, although the laser like stream of hot air from the SSV can overcook if your heat is high and you don't move the bowl around a little. The SSV is tops in vapor to air ratio-definitely richer hits than the Extreme. The guy who now owns my V-Tower also has a nice box vape and the Vapir Oxygen Mini, and the V-Tower is his favorite for home use. The Vapolution can be very efficient but only if you're very patient and careful. If you're not you can burn your bowl very quickly. The Purple-Days is the most efficient electric vape on the market IMO, but it certainly doesn't give you bag use (or the big whip hits). Only you can decide what's most important to you.
I don't think you'd be much happier with the Volcano. It's high quality, but the Extreme and herbalAire are its equal as far as producing good vapor. I also agree with stick about loading less for more efficiency. When I loaded twice as much in my herbalAire, it never seemed to give me twice as much vapor.