Here's my anecdotal story about using my credit card insurance for my rental car (sorry for the long story, hope it helps in some small way):
My family was finishing up a trip to Texas for my brother's wedding when I was on the interstate heading to the airport to fly home. When I had picked up the car a week earlier, I was kind of pissed because they were out of compact cars, and had 'upgraded' me to a tank of a Jeep SUV. Anyways, about five minutes from the airport and the conclusion of my trip, a truck a few vehicles in front of me in the left lane dumped a load of tree branches onto the interstate, causing a chain reaction of hard braking. Plenty of time for everyone to stop, but the girl behind me in the compact car was texting her boyfriend and slammed into the rear of my vehicle at full speed.
When I pulled over and stepped out to inspect the wreckage, I first see that her car was completely and utterly totaled. I then looked over to my Jeep, which had a scratch and a loose exhaust pipe. Thankfully everyone was physically ok.
The police showed up, and it appeared the police officer was the girl's buddy, as she didn't get ticketed, but the guy who dumped the trees did. The girl even hugged the cop after it was all done.
I finished my drive to car rental agency, pointed out the minimal damage, and asked what to do next. They said I would be contacted, but the party-at-fault's insurance would likely cover it. I then called my credit card company, and they too informed me that the party-at-fault's insurance would likely cover it, but I could fill out the paperwork if desired.
I declined filling out the paperwork, which turned out to be a mistake. Over two months later, the car rental company calls to tell me that the other party had fraudulent insurance, and I was on the hook to cover the damages (~$250). I called the credit card company (Capital One), and they stated the paperwork needed to be filed within two months of the accident, but they would allow for a waiver if I can get a letter from the rental car company (Enterprise) outlining the situation. I called and emailed the rental car agent handling my case, but she thoroughly ignored me and promptly sent me to collections. Two years later, I think the collections agents finally stopped calling me on a daily basis.
TL;DR: Seems like credit card insurance should work, but in the case of an accident be sure to fill out the paperwork even if you don't think you'll need it.