A definition is in order.
A Ratchet Buckle uses a spool and a lever to tighten the webbing. They have a ratchet wheel and a dog that locks the spool after each move of the lever.
A Cam Buckle uses a spring loaded cam, usually with teeth or ridges to pinch the webbing. Much lighter and simpler than a ratchet.
I have hung from high quality cam buckles (Northwest River Supplies and StrapWorks) with no problems. And I am a Certified Big Guy. Personally, I would not trust the cheapies one finds in big box stores or other such locations. I have cam buckle straps because I car-top canoes, and I want the best quality straps available. Saving a couple of bucks on a strap and losing a boat to the slipstream is false economy.
Same with hitting the ground due to a cheap strap.
My 2 cents.
Ditch the Ratchet Buckles
I am currently using webbing from a box store. They were sold as tow straps; a 4 pack of 12 foot orange and a 2 pack of 15 foot blue. My friend and I bought two 2 packs and a 4 pack (that's 8 pieces of webbing for those of you counting). They are weight rated at 900 lbs. I weigh 260 and have had no problems (knocking on wood).
They were 7 dollars for the 2 pack and 16 dollars for the 4 pack. We could have just gotten four 2 packs but we wanted to color coordinate our head and foot ends for ease of setup. They already have a sewn loop in one end which is unfortunately attached to a black metal hook. I rented a pair of bolt cutters from my local hardware store for 7 dollars and cut all the hooks, ditched the ratchet buckles which aren't actually attached to the main piece of webbing, and now had 8 pieces of webbing with a sewn loop in the end. Throw a carabiner in the sewn loop and throw it around a tree and snap onto itself and you have 8 pieces of polyester webbing for 30 dollars. That's 78 feet of webbing at 38 cents a foot.
I know the thread is about ratchet buckles. My argument is that you can get a cheap pair of tow straps, ditch the ratchet buckles, and have a true permanent suspension solution.