After having a protected Trustfire "blow up" in my mechanical mod, I will no longer use any battery with the name "-fire" in it.
I only use the red AW IMR batteries in my mods. They are safer chemistry batteries, which means the chemical components within them are less volatile and less likely to explode than the volatile chemistry protected Li Ion batteries, which often have the higher mAh ratings (which are rather deceiving in real use).
Having said that, no battery is completely safe, even the battery often considered to be the safest, the red AW IMR.
http://www.e-cigarette-forum.com/fo...-battery-failure-imr-18650-a.html#post3265928
Regulated mods (variable voltage/variable wattage) have built-in protections against atomizer and battery dysfunctions. They should shut down and refuse to fire when they detect a problem. And because of the boost circuitry that they employ to increase voltage higher than the battery itself, require the high drain IMR batteries, and not the protected variety.
Having said that, the more layers of safety that you can use, the safer you will be. Using a 2 Cent or Vape Safe Mod fuse offers an additional layer of protection against a hard-short battery.
Batteries : Vape Safe Mod Fuse 2
It's my opinion that safety should be the number one priority in choosing batteries, not an inflated mAh rating, and only high-quality brand-name batteries (AW, Panasonic, Efest, Sanyo, Sony) should be used in PV's. Generally speaking, IMR safe chemistry batteries are safer than protected Li Ion batteries, and a high quality battery recharger (Pila, Nitecore, Xtar) is just as important as high quality batteries.
Some important information resources on battery and mod safety:
Basic to Advanced Battery Information from Battery University
http://www.e-cigarette-forum.com/fo...9007-warning-rechargeable-batteries-apvs.html
http://www.e-cigarette-forum.com/forum/ecf-library/129569-rechargeable-batteries.html
http://www.e-cigarette-forum.com/fo...4690-protected-batteries-vs-imr-safety-5.html
Mechanical Mod Proper Usage Guide
http://www.e-cigarette-forum.com/fo...-ecf-metal-tubemods-safety-specification.html