I would suggest MTL root grapple. I have one and its real heavy (1100 or so lbs). Can handle anything you throw at it and will not bend. Your FEL would be the weak spot it something happened
Personally Id rather bend the grapple than damage something on the tractor. If you go too heavy you lose too much carry capacity and might get over confident on the tractors capabilities.
I went with a no-name root grapple based on price figuring it would be cheaper to make repairs than to make a new one from scratch. You get what you pay for in the end. Ive had to replace the pins, do a bunch of re-welding. Bent the tines. Bent the thumb. Holes look like they were made with an acetylene torch. No bushings or grease fittings. Buttered welds.
Dont go by weight alone to decide what HD is...a lightweight grapple made out of AR300 steel would be better than a really heavy unit made from mild steel. You are buying a grapple for the tractor to move stuff with, not waste energy moving a heavy weight on the front end.
I dont think I would buy off the internet again without having a close look at the unit in person.