Starting day 2 with the Darwin...
On a starting note, just like with any variable voltage mod, I do not recommend using LR atties or cartos on this unit. They just aren't necessary.
And just for fun, I put on a used carto that I was going to toss out, cranked the Darwin up as high as it would go, and hit the button. I kid you not, the vapor was pouring out of the carto like steam out of a teapot, creating a plume that shot out about a foot.
I am just as happy with my "RedneckDarwin" today as I was yesterday. I call mine the "RedneckDarwin" because it is ugly as sin. The newer model board and batteries don't quite fit this older beta case it was put in, and it was making the case "gap" a bit on the end, so I took some duct tape to close that little sucker up tight. It makes for a handy little grip, but kinda makes it look like it was made in a high-tech trailer park.

The reality is, however, that it is more like a rusted out old AMC Pacer with a Lamborghini Diablo engine hidden inside. I've opened it up and took a look under the hood, and can see that a lot of thought went into designing this unit, from the dual LiPo cells to the well thought-out circuit board, and even the neat way they designed the swing arm to make it work the way it does. No, I won't go into too much detail (yet), or show pics of the inside, but it won't be too much longer before all that info is out, anyway. I can't wait to see what the final case design will look like.
I spent most of the night last night using a 510 atomizer on it, and direct dripping. (I really need to get a VapeMate... argh). It was great. There is no need to even look at the display if you don't want to, as dialing in the perfect setting for you is incredibly simple. Start off low, then just increase it little by little until it is exactly where you want it to be, then just vape your heart out. Very user-friendly.
I also spent a little time vaping in front of the mirror, just to I could watch the display as I used it. (The old eyes aren't good enough to watch something that close to my face). The voltage and amps will change as you vape, showing the Darwin adjusting to maintain a consistant wattage.
Going strictly by the usability and functionality of the device so far... I will definitely buy one as soon as they are available, and I'll be pretty sad when the time comes to send the beta unit back. I will miss my RedneckDarwin.