I've crashed twice with sliders. First time at relatively low speeds, they worked well and prevented any damage to the frame and saved my side fairing. The upper and the tail took a beating, probably would've been a write off had I gone through insurance.
Second time was at the track (~100kmh), I crashed and while the sliders did prevent any damage to the frame, my fairings were thrashed. Every single piece. Again, they did their job at protecting the frame but the bodywork itself was toast.
IMO, the likelihood of writing off your bike on the street is very high even if it's a light crash. Too many objects to come in contact with to cause real damage to the frame, in which case, sliders would likely not help. I'm only installing sliders on my street bike in the case of tip overs.