Oh, I forgot to mention...I have found that HV atties really shine on this thing and work the best. 3.0 - 3.5 ohm is the sweet spot. I really like the be112 with a stealth 510 to 801 adapter and I like a HV 510. I generally keep it around 7.2 or 7.4 watts and this reads 4.7 or 4.8 volts. I've even tried a 510 to 510 extension and used an ego T
tank on it. I just kept the watts adjusted so it didn't go over 4.2 volts with the t
tank.
I've also noted the advantage of having a built in meter. I have so many atties lying around. I just have to pop them on the Darwin and it reads what ohm the atty is for me.