Higher voltage is the key for longer runtimes. I not only get 14+ minute runtimes but beat nitros with these little guys. With higher voltage you can make more power with less current (Amps) thus achieving better efficiency (runtime)
You should see if Mike can get you some 2200's otherwise pm me.
These cells cost around the same as GP3300/3700's but they weigh a third less. I notice a definite performace gain with less weight.
Here's the list of GP batteries:
Gold Peak
Here's the specs on the 2200's:
GP 2200's