Jeremy, I have an iStick, 20 watt, that I got when they first came out. I don't use it all day, every day, but it does get daily use with a Fogger on it. It's working fine after about three months if that's any help to you.
I also have an IPV2, 50 watt, that I also got when they first came out. It's solid as a rock and gets used, heavily, daily with a Big Fogger on it. It's a single battery and a little small in my hand, size 11 glove. The dual battery would probably be a good fit for me, but I think a 134 is a small tube mod, LOL.
The newer iStciks are supposed to have upgraded 510 connectors and spring loaded center pins along with some other, internal, upgrade. At the price, if I were looking for another VV/VW device, I'd probably go with the dual battery iStick. That said, I'd also go for a dual battery Vapor Flask, even at their price, with a DNA40 chipset. I am waiting for DNA40 boards and plan on building my own mod with them.