I have 8 nanotechs 5000mah and 2 6000mah batterys, and none of those have puffeded.
Atleast its better to buy turnigy at an decent price than other chinese cells with an "brand" name sticker on them.
Hyperion use korean made cells.

One thing that is important no matter what brand you use is to never discharge the cells below 3v, if you do that it will quickly get damaged and puffed. I recommend to use a device like junsi cell-log, cheap insurance. Some charger have inaccurate balance circuit=quickly damaged lipo