I've had the Gemini Duo kit for just over a week now, which includes the heavy hitter atomizer. To round out the package I also purchased the usb car adapter, usb battery charger, and three e-liquids: tobacco red, triple five blend, and cherry.
Atomizers
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I don't know the technical specifications of the atomizer, but I can give you my take based on a week's usage compared to the standard "red" atomizer.
Overall I've found the heavy hitter to be the smoother hitting of the two units. The heavy hitter yields a fluffier mouthful of flavor and vapor as compared to the standard. The actual vapor output is only slightly more, but it looks and feels fuller. I don't think it's the miracle atomizer that everyone's hoping for, but it's definitely a little more satisfying than the standard.
I'm throwing around subjective terms, so allow me to explain the standard atomizer comparatively. While not at all bad, it's harsher than the heavy hitter. The flavor seems to hit me in the back of the throat along with a slight taste of the atomizer after a long pull, and the vapor output is more airy. Conversely, flavor from the heavy hitter tends to be more diffused without any atomizer taste.
If I had to come up with an analogy, I'd say that the heavy hitter is whole milk, and the standard is 2%. Though there is a downside: for some reason I seem to get a stronger throat hit with the standard atomizer (and I define throat hit as the resistance I feel from the vapor being drawn into the upper respiratory tract). It's definitely there with the heavy hitter, but it just takes an optimally filled cart or a focused pull to achieve. All that said, if I had to just pick one or the other it'd be the heavy hitter.
E-Liquids
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Tobacco red is very nice. It has a sweet tobacco flavor with very subtle cherry after taste. Triple Five is equally good. It has a more dry roasted tobacco taste with a hazelnut undertone. And tastes may vary, but I can't stand the cherry liquid. It has a black cherry flavor that's annoyingly artificial, and once I vaped it, it was hard to get off of my palette and atomizers. In addition to my gripes, I couldn't get a decent throat hit no matter how good of a pull. The tobacco red tends to be a little sweet, so after I can't take it anymore I switch to the triple five, which tends to be a little dry. And on and on I go. I'd be very interested to hear if anyone's tried the hotel or golden liquids and how they compare to the other tobacco flavors.
Batteries
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The kit came with one each type of battery, manual and auto. I'd have to say that I like the manual battery more, although I tend to chain vape so it run it down pretty quickly. As reported, once drained the batteries take about two hours to fully charge, and the PCC takes slightly longer. I don't know if this is normal 510-ish behavior, but from other reports the charge time seems excessive. With careful planning I've managed to make it through each work day just fine, but I find myself looking for a usb passthrough for my marathon chain-vaping evenings.
I did run into an issue where my manual battery button popped off, and then later encountered another problem which caused it stay pressed internally killing the battery. I emailed customer service and had a new one in three days at no charge. Of the two, I prefer the manual. With it, I get a consistent throat hit enough to keep me away from analogs.
The PCC
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The PCC is internally cramped. To maximize carrying capacity they made the slots for carts a little too close together which often requires removing multiple carts to get at the one you're aiming for. Not a big deal. The material inside is hard white plastic instead of rubbery foam. The downside is that things rattle around inside and liquid from re-filled carts ends up in places where it ideally shouldn't. Again, not a huge deal. If Revolver had a cap solution for the carts this would be a non-issue (hopefully soon). Overall though it's pretty damn good. Same unit as the Blu or Volcano PCC, just modified to accommodate a larger battery type (both auto and manual). It holds two batteries (one charging slot), one assembled atty/cart combo, and five cart slots, one of which can be used to store the spare atty. For what it is and what it does, I think Revolver did a great job here. A couple of gripes on my part, but nothing major.
Sorry for the long-winded reply.