I don't trust Efests. I've heard too many reports that they are really LG
batteries with lower current ratings (20A), and too many reports that if you actually do run them at 35A they get a tad warm. Having said that I have run purple Efest 18500's rated for 15A down at 0.5ohms with no problems, but I wouldn't push them any further than that. I think the VTC-4s are the safest, but the VTC-5's big 2600mAh capacity does it for me. After 2 hours of 0.3 sub-ohming I would expect serious battery depletion, so I pull the VTC-5 and meter it, and it's still up at 4.0V. Two hours later and it's up at 3.9V. Simply awesome. When they get a bit flatter, they seem to hover on the 3.7V level for ages. I wouldn't buy any other
batteries than the Sony's now, they are sweet batteries. I kinda dig the green wrapper too.