I used their warranty once for a handheld Ultra Stinger that I used for work. It had inadvertently fallen onto the pavement from where I was working above, and 10 seconds later a truck that was backing up backed right over it.
I was not happy about it because the light was almost new. It bent the tube and ruptured the battery cell inside. I thought I was out ~$140 and would have to buy a new one, but our tool rep gave me a new one on the spot and sent the damaged one back to Streamlight. They warrantied it no questions asked.
That kind of service sold me on Streamlight. I currently own five TRL-1 lights that I have mounted on long guns. I own six various hand held Streamlights, and lastly one of their headlamps. So far, I have not had any issues with any of them over the years. Granted none of my TRL-1's see anything resembling duty use, but several of my handhelds see hard use daily.
That is my experience with Streamlight. I like their products, and my experience with their customer service was excellent.