The SBL Ego V3 is variable voltage only as far as I know, but has the strength of it can go up to 6volts over the itaste vv v3 only does 5volts or 11.0 watts, and you have that extra 1300mah capacity.
The itaste vv v3 uses a micro usb that can be usb passthrough like the SBL Ego V's mini-usb connection, so both actually have the strength of a passthrough, though the itaste is 800mah still has plenty of power for most vapers. The biggest strength the itaste has is that the itaste vv v3 uses the same chipset as its bigger brother the MVP V2 though you can't use it as a external charger to a cell phone or such like the MVP, it still has all the other features, Variable Voltage or Variable Wattage, atomizer resistance checker, battery level checker, and the annoying puff counter. I've owned an SBL Ego V2 1300mah, as well as I currently own 2 itaste vv v3's, and both are great performers as backups to my MVP and SVD when out and about and for sitting in front of the computer
vaping while charging my other units.