Those TP 1320's get for sure double what the stock NiMh packs get.

I had two TP1320's, and the stock pack and I was well entertained for an hour. Surely a good 10 minutes of actual flight time with a TP 1320. I did not time it tho...

Also, the TP1320's die more gracefully. When they are done you know it, and you're done. The NiMh pack dies more slowly, and the aircraft gets very naughty as the pack slowly dies.