Batteries for a 1350Kv Tekin

[Trick440]

Just got a Revo with the Tekin Gen 2, RX8 1350kv Motor/ESC.

It came with 2, 11.1v, 5500mah batteries. I have ran this only a few times and for short periods, never ran the batteries out. I think they last a pretty long time.

But, I know I would probably like the longest run time possible. Looking up longest run times and 2, 7.4v, 9000 mah batteries from SMC came up and I was planing on ordering these. Except now I'm reading this 1350kv motor is best with 6 cells. Should run the 7.4v, 9000mah setup or look for a 11.1v, high mah setup?

This isn't for racing, just want to have fun with long run times.