I've used a pair of Rhino Ramps for at least 15 years and they still work fine. No damage, no wear, no issues, ever.
With my new Tacoma, I wanted an easy way to get the truck in the air to apply Fluid Film and other tasks, so I bought a second set of 12,000 lb Rhino Ramps. Using four ramps also gets the truck a few inches higher in the air than I can accomplish with my floor jack and stands, and the extra clearance makes some jobs easier.
I insert the ramps tightly under the front of the tires and slowly creep up them in 4L. Once at the top of the incline, I shift to Neutral and ease off the brake, allowing the tires to settle into the platform, between the stops. I put the truck in Park, set the Parking Brake, and remove the keys from the truck. Climbing and parking on the ramps is a very slow, deliberate process. My concrete garage floor is nearly level with a fairly rough finish, and the truck appears to be very solidly supported. I've done this a few times with no issues.
As I was tossing the packaging, I read a warning that the ramps are only to be used in a front or rear configuration, not both on one side, and not on all four wheels. I know the truck is well under the weight limit of 12,000 lbs/pair, and the tires fit well on the platforms at the top of the ramps. My guess is that if care isn't taken to make sure all four ramps are placed, climbed, and chocked properly, someone could dump their vehicle off the ramps. Used as I described, I don't see that as a problem.
Knowing that I may be missing something important, does anyone see a problem with using four ramps as I described?