Earlier Joye eGos (without any following letters), and the eGo-t have a regulated voltage of about 3.3V. The eGo-c has a regulated voltage of about 3.4V. The eGo-c 'upgrade' and eGo-t 'upgrade' batts have two modes - one where the voltage is regulated to @3.3-3.4V and another mode that is unregulated where the battery goes
through the normal "3.7v batt curve" - 4.2V off the charger, 3.7-3.6V for most of the cycle and to @3.2V at the end of the charge.
And yes, that is what you would be experiencing vs. the KO or KGO or any
mod that has a 3.7v batt unregulated. The one thing nice, imo, about the eGo-c 'upgrade' with the 2 modes is that if the unregulated mode is burning ejuices, you can switch to the regulated mode using the same ohm coil/clearo.
Of course you could 'solve' that problem with a VV batt as well, but if like me, you like the length of regular 650mAh batts vs. the longer VV batts, then the 650mAh eGo-c upgrade is a good choice. You may have to take two with you when you go out, but I do that anyway to have a few different flavors without having to change out clearos/T3's.