i dont know much about the SB but I just ordered a provari. Its due in the mail today so I dont have first hand experience yet, but from all my research it is a very good
mod. Plus being VV means that you can dial in the voltage to find your sweet spot. Got an LR, tune it in to 3.7ish, got a standard res, dial it up to 4.5. Got a high resistance atty, crank it up to 5-6. That old atty not performing as well as it use to? dial up the voltage and make it perform again. It also has a built in ohms checker and a lot of safety features to prevent damage to the unit such as short protection, thermal protection, reverse battery protection.
The standard unit uses a 18490 IMR high drain, and you can buy an extension cap to use 18650 IMR high drain. I ordered mine with 2 18490 batts and a charger for just shy of $200 out the door. Variable Voltage provides you with so much diversity its like having many
mods in one. You have a 3.7v, 5v, and 6v
device and everywhere in between all in a single well built package.
I'll let someone else comment on the SB, as I said, I know nothing about that one. Good luck and vape on!
Edit: I forgot to mention the best part! The digital readout. No need to bust out the multimeter to know what your voltage is. It tells you right on the screen. It also increments the voltage by .1 from 3.3 to 6.0