Yes these Panasonic cells have been tested over and over !!!! A large # of BLF members don't use anything else .....
The problem with Trustfire is they tell you 4000maH and some are 2000maH .... and some BLF members have unwrapped their Trustfire batts bought the same day from the same seller and on the body every battery has a different serial # on the body meaning they are recycled batteries ! Sometimes is better to pay a bit more to get better results !
REAL TF flames are very good for the price. Protection circuit is still very important when running batteries in series, e.g DRY, where reverse charging is a real danger.
Trustfire, however, has too many fakes running around. I find it hard to give recommendation for it just because of this, as anyone can run around and buy the cheapest TF they find on eBay, just to find out it sucks big time. Even worse if the circuit doesn't work.
For budget use, I would go for both of these, Panasonic for best capacity/price, and Manafont 2400TF flame for its protective circuit.
Can anyone show any proof of a unprotected Panasonic cell having a catastrophic failure? If protection is there to just protect against a crappy cell in the first place, why do you need it on a quality cell? Reverse charging only happens when you have a large mismatch, with careful use this can easily be avoided and would actually be hard to achieve using a pair of panasonics and common sense. One of these cells will also have a good chance of not exploding on you even on a dead short.
Just because there is no proof doesnt mean it cant happen. PCB can also be good if you dont want to deplete the cell too much.. yeah those Pannys are considered very safe, probably the safest, thats why most laptop cells and electric car battery packs use them. But I still understand people that prefer having a PCB. :)
Reverse charge can happen easier thank you think. Which is why I dislike serial light. I give an example, e.g DRY, 3 batteries. How many chargers with 3 bay? Very few. So quite likely the user will charge two at a time.
And all it needs it just that one time when the user forgot that one battery hasn't been charged. Two fully charged + 1 depleted battery = reverse charge. Easy.
Panasonic is designed to withstand dead short. But nothing is stated about reverse charge, where the polarity is totally reversed. I guess we won't know what really happens with reverse panasonics until somebody try it out :) but I'm not going to recommend unprotected batteries in series until it is proven safe.