I just upgraded to the iStick 50W. After having it for 2 weeks I bought a 2nd one for a back up. I had a spinner2 before that. I top my 50W with Nautilus Mini's and it's a great vape (I am using 12W mostly). The biggest feature of the Istick 50 that appealed to me is the 4400 mah, I can probably get 2 days before recharging it. It is a pass thru charge on the back side using the same plug as the iphone. It's not as large as most "box mods" and is smaller than a pack of cigs.
You can see the pass thru charge port in this pic. I also bought the 510 to ego adapter to use my ego tanks.