INFO: s stands for serial and p stands for parallel, might be obvious / might spare googling

I'm trying to find out what would make more sense. I have 4 cells of 2750mAh and I want to use a second cell to upgrade this device. So I have to decide - do I want more voltage or more capacity. I have this 2-6.8V input to 5V-20V output converter which is fixed to 12V (note to myself: I should check that) and could get some step-down regulators for 5V and 3.3V when I use the 2s1p configuration. OTOH, when I use the 1s2p configuration, I probably still can use the 12V booster, get more power and could use a buck booster for 5V. Not sure about the 3.3V vs. drop-out voltage of a 1117 though. I could add a direct out of the lipos, but it sounds a bit dangerous having them out in the open.

In case of charging: I'd use a lipo usb 1A charger per cell and a switch capable of switching the cells into charging mode vs. use mode. I might even switch between 1s2p and 2s1p, if it is plausible.