The amethyst (Purple) Pax is apparently ready early, because I got mine yesterday. This first thing I wanted to test was a very small quantity of bubble hash because that's what I primarily use right now.
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In that trial I had the Pax on medium and had the oven on for only as long as it took for the light to turn green. I found I get better results if I have the Pax on high, and let the hash cook in the oven a bit longer.
It usually takes only a small pinch in my Arizer Solo stem to get me very medicated, and for heat delivery I've used the Solo itself and the SSV, both of which work very well. The SSV (with the default glass parts) has been the most efficient so far, because I can direct the stream of hot air right at my little hash nugget. The pax doesn't do so well with very small quantities.
I also vaped some of a friend's Bali Shag tobacco with it, and it vaped nice and smoothly. My Pax gets quite hot after a few minutes of continuous use. I'm not sure if this is normal. After about 5 minutes of being on constantly, it's almost too hot to put in my pocket and the oven cover is hot enough to cause a burn. The mouthpiece also gets hot, but not as much as the part of the aluminum body that the mouthpiece fits into. If your lips touch that hot aluminum it can be unpleasant.
Overall I'd say the Pax is a great device, but it excels at a very specific kind of use, namely a full oven and occasional hits, turning it off and possibly stirring in between uses. I tried the cigar puffs that slim mentioned but that didn't give me very good hits with bubble. A long, slow drag seems to work the best. It's not really good for having on constantly for more than about 5 minutes. It gets too hot. But that seems to be the only way I've successfully been able to vape bubble. As such, it is not ideal for my typical usage. I think I would need a purely convection type vape for that. If you vape herb one or two tokes at a time, you're golden with the Pax.
Of course this was my first impression after one day's use. Perhaps I'll change my mind later.