single 4s or.....

[_paralyzed_]

yes, 2 x 2s 5200 would yield 200mah more than a 4s 5000. But 200mah really isn't much, maybe another minute or two of runtime.

The MMM can handle 2 x4s IF THEY ARE WIRED IN PARALLEL (positive to positive and negative to negative) And if you had 2 4s 5000mah batteries wired in parallel it would equal 10,000mah and give you twice the runtime.

The MMM CANNOT handle 2 x 4s wired in series, that doubles the voltage and the voltage limit is 6s. (2 x 4s wired in series equals 8s)

Any other questions?