To be honest, my experience with Streamlight has been the exact opposite over the years. Mine have been utterly reliable except for two models.
1- Streamlight Nano ~
Avoid at all costs. Whether carried on a carabiner outside a pocket or tucked into a pocket, the head loves to unscrew itself as you walk. Had mine on a carabiner with my house-keys. At work, at night, in the bathroom trailer. Reach down, and something felt off. "Off" being the key word. The head was missing. And of course, so were the button cell batteries. I was so angry! Unclipped it, tossed it in the garbage. The 1-inch lobster claw clip is honestly the best part of the light.
Next day, same trailer, someone found the head and apparently left it for me to find; on top of the hand-dryer.
2- Streamlight NightFighter (Incandescent version) ~
Horrendously awful design that was clearly meant to compete with the SureFire C2. Apparently no one actually put it in their hand before releasing it to the public. Grip-ring, huge, horribly uncomfortable. Clearly designed for some sort of space alien's hand because no human one could use it. And, bizarrely, came with a flush tailcap switch instead of a protruding one. Clip mounted on the ridiculously oversized grip-ring. Thus, making the clip useless. Tried adjusting the position of the grip-ring. Yeah, don't do that! Lost the tiny nut that held it in place. Couldn't find it! Ironically made the light better because without the grip-ring, the N.F. was the shortest 2xCR123 flashlight on the market at that time!
Actually had an opportunity to talk face-to-face with a Streamlight executive. Had heard that a new LED NightFighter was soon to be out. Expressed all of my concerns regarding the incandescent version. Told him I was looking forward to the new design LED version. He acted like he was genuinely interested in my feedback as a customer. Couple of months later, LED version is released. It's the same damn light! Only changes, uses an LED and has two rings on the bezel. Garbage design. Whoever created the N.F. not only deserves to be fired, but sued so the company can get back all of back-pay from him that they are clearly owed. Would honestly love to meet this incompetent moron so I could tell him off. He absolutely deserves it.
So, there you go. Two miserable failures out of over two dozen Streamlights I own. Both due to design flaws.