Keith I don't buy it! You say all of the traps I listed will break legs on gray fox even with 10 swivels...nope. Maybe on certain especially fiesty, rollers but I've caught alot of grays in big traps with non offset jaws have you..that were fine. Now I'm not saying a big non-offset trap is my first choice on grays...a #1 1/2 offset with perfectly rounded jaws, centered chain and multiple swivels in a grass free, soft, bone dry ground with pillows on each side of the set would be...to prevent damage...lol
Let me throw this out for discussion...what has your been your experience in chain lengths for grays and damage? Personally, chain length might be the cause for alot of possible damage in these light boned critters.
FOR STRICTLY grays...a shorter well swiveled chain might reduce the potential to build up speed on these aggressive rollers.
But I think you are refering to paw damage due to trap jaw contacting paws. An strong offset jaw, with a wide surface area will not necessarily damage a paw. I believe the weight of the trap plus the length of the chain and swiveling will possibly have more effects on the little grays paw...my opinion.