I really like our Darwin because as an atty or carto changes during its life span the Darwin will adjust the voltage to always maintain the same watts(heat) even if the resistance(ohms) changes. It is also very easy to adjust the watts up or down by simply rolling your finger on a button. And of course you don't have to mess with batteries. Just plug it in over night and it is ready to go again for another day. Saying all that I also have a Provari. It is also a very nice PV. Fully adjustable on the voltage and very nice engineering work of art. Both PVs are great and worth saving up for...