Call LW to verify and ask if there have been any reported failures or have a buckle failure rate. If the "sticks" are rated at a certain poundage, it would be for the weakest link in that stick system including the belt or buckle or axle or bolt or.... Usually there's at least a safety factor of 2x or 3x or more built in to "maximum ratings" for safety & lawsuit purposes, but don't push the insurance; it'll save your life.
I've used my originals for 6 years w/no problems...about time to get new ones - getting a little fray on some of the webbing. Absolutely no problems with the buckles slipping or breaking. I weigh 200# geared to hunt. Watch their instructional videos on how to use LW equipment. Some users don't and therefore, don't climb, use, tie-off, or stabilize their products properly - and pay for it the hard way.