Buddy of mine bent one fork about 30º, due to not paying attention. While tramming on a gravel road after loading logs, noticed a branch/large twig stuck in the loader/bucket frame area. Tried to wobble the bucket frame to dislodge it, un-curled too far without lifting loader, fork caught the gravel road and tractor came to an abrupt stop!
I have acquired a set of forks from a 5k lbs rated fork lift, and plan to make my own quick attach frame to match my John Deere loader bucket. My little tractor has limited lift capacity but my neighbor has a much larger JD with same style loader, we may have the opportunity to share equipment.
My opinion would be that the heavy rated forks will not be substantially heavier than the lighter rated ones, but be much more able to handle any abuse you may put them thru.
Good luck, forks are a very useful addition to a tractors ability.