I thought APV stood for Advanced Personal Vaporizer... Good to know.
Are any of these clones better than the others. My need to play is strong. Even if the chip dies I have the tools to mod in another.
The Kangxin is pretty ropey in terms of build quality. The Waidea is much better, close to 1:1 in terms of fit and finish. Then the new SXK is my current favourite: physically it's mostly good, although the black suffers from anodized gunk in the battery threads which usually requires scraping out. Some people also need to remove the top plate and sand the underneath, and top of the mod, for the same reason. The Waidea used to have that problem even worse - because it lacked a proper ground cable - but Waidea have said that has been fixed. I'm not sure anyone's bought a Waidea recently and reported back.
A downside of the Waidea is it doesn't have floating/sprung 510 pin, nor is it adjustable. I have a couple of attys that won't register on it unless I adjust their pins quite a bit. The Kangxin is not sprung but it is adjustable, but that goes wrong a
lot.
The SXK is my personal choice both because it has a sprung pin (quite a good one), and more because it's the most advanced chip. It suffers from a low resistance problem (which I have informed them about and they have promised to fix), but it also has a feature called Nickel Purity which allows one to adjust the Temperature Coefficient of Resistance, the number used in TC calculations to turn the resistance rise into a calculated temperature rise. This means the SXK can be changed to readily support TC vaping with Titanium and Stainless Steel wire. Titanium is possible on authentic DNA 40s, and clones, with a temperature offset, but Stainless Steel is not.
It reads all coils at least 0.04Ω too low, and can be a lot more. This affects the accuracy of TC. However Nickel Purity can be used to adjust for this - a higher than usual NP setting compensates for the lower-than-real resistance calculation.
Other advantages are that it's 60W versus 40W for the Kangxin and Waidea, and supports °C temps, if you care about that, and it has a slightly larger, crisper screen. (Though it's also very hard to see in direct sunlight, unlike the Waidea.)
See my detailed full review of the SXK flask in this thread,
here.
For much more discussion on TC vaping with wires other than Ni200, including more discussion on the SXK Nickel Purity feature, see my thread here - I explain a fair bit in the first two posts:
TC beyond Ni200: Nickel Purity, Dicodes; Ti, SS, Resistherm NiFe30; Coefficient of Resistance
Out of the box the SXK vapes pretty well with Ni200, because they already adjusted Nickel Purity up from its standard Ni200 figure, compensating for the low resistance. For other wires like Titanium and Stainless Steel, one can vape them pretty well by adjusting NP a little higher than would be expected from that wire's TCR. That won't mean much unless/until you read the above thread - for now all you need to know is that if you want to TC Vape Titanium (which is recommended, it's a great wire), you would set NP to 40. For Stainless Steel, a figure of 11 or 12 is likely best.
In terms of absolute TC accuracy, the SXK is not
great. It fluctuates about a bit, and its TC response is a little.. jerky. Sometimes you can hear it almost 'pulsing' the coil, as it applies a wattage, then stops, then applies, then stops. The Waidea is definitely smoother, more like the authentic DNA. But I still get good TC vapes off my SXK and I love the ability to properly vape Titanium and Stainless Steel, something almost no other currently-released mods (even authentic) support. Though more and more are adding Titanium and some are considering Stainless too.
I plan to do TC accuracy testing of both of them with the thermocouple thermometer I recently bought, so I'll have more absolute figures soon.
TLDR: The Waidea is a good flask, the SXK is arguably a better flask in several ways especially the sprung pin and ability to easily TC vape wires other than Ni200. But there's a couple more things you might need to know about using it, and if you get the black you will probably find yourself doing a fair bit of scraping/cleaning to get it working reliably.
You can get the SXK from FocalECig here:
Silver;
Black
The Waidea flasks are on 3FVape here:
Silver;
Black
Oh,and yet another option is the Waidea Squonk clone - single battery with built in bottle and bottom-feeding 510. That's
here on 3FVape, but not yet released. It'll have the same chip as the Waidea VF, and I believe also the same fixed, non-sprung 510 but I might be wrong about that.