Here's what I did, am now a happy camper. Had two isticks. Love'd em. Gave me a chance to explore the more advanced mod technology available now at a low price point. Two-three moths in, the dreaded 510 connection problems arose, mainly on one. I put the better working istick aside before it too dies, thinking it'd back up a new mod, and went looking. Wanted something small/stealthy like istick, capable of highish wattage, well built. Centered in on Vaporshark, which is built like a tank, killer button, great reviews, solid company. Considered the DNA30 and rDNA 30 (this is before the 40 was fully available). Difference is rDNA uses 18650 replaceable battery, the regular DNA is a non-user replaceable lipo pack. I have 18650s for my mechs, but I ended up going with the regular DNA30. Maybe because I carry around charge gear for my phone, maybe because I had the very long-life and equally tiny istick as a backup. I am very stoked on the vaporshark, its just as small as the istick, the batter life is good enough, feels good/better than istick in the hand, has a killer button and more options (stealth mode, wattage lock). With the sharkskin case/cover, 22m atty's are flush (no overhang). I recommend the DNA30 or rDNA 30 for sure. $119 is not cheap, but it feels like it will last, has warranty, fair repair and battery replacement service.
Now, the 40 is out. More buggy, more expensive, more technical with the temp protection. For me, not vaping higher than 20 or so, I didn't see the real benefit.
Last, DNAs can fire sub-ohm down to about .5 ohm I believe. But the thing with DNA regulated mods is, in my opinion, it's not about subohming. the high wattage options provide the same power-to-coil that sub-ohming seeks. But the option of sub-ohming is there. HTH
