Welcome to TBN.
Why did you choose such a wide grapple? If only picking up trash it would make sense but for more aggressive brush clearing I think you'd find a narrower version more effective as well as lighter and cheaper. Width of a grapple does not need to be the same as the primary bucket and there are many occasions where a narrower grapple (even 48 inch) is better as it allows you to concentrate force rather than distribute it over a wider area. The video at everythingattachments shows the two tasks for which a wide grapple is effective but for almost everything else a narrow grapple has advantages. Don't be fooled by thinking that a wider grapple can lift more debris, a lighter grapple ultimately has a greater load capacity and as brush sticks together a narrow grapple can gather just as much brush.
I like their basic design which is essentially an improved version of the Millonzi grapple I have with a better engineered top grapple design. Interesting that they chose T1 steel for this grapple. Mine is made of mild steel and has held up well using a 40hp tractor. I have bent a tine or two over five years aggressive use but with mild steel it is no problem to heat and straighten or to use simple welding methods to add gussets etc. T1 is obviously stronger pound for pound but less easily repaired and more expensive.
I wouldn't worry about hurting the grapple. I really haven't hurt my 300lb 48 inch 3/8 mild steel grapple using a similar sized tractor to what you have. If anything, the wide grapple could hurt the loader if you snag a buried rock or stump on the grapple outside edge while root raking the way he shows in the video. Best to keep the grapple "inside" the FEL arms when doing that sort of work to minimize torque forces when hitting a big object.
Again, I think they have a nice design but there very few tasks that need a double jawed 72 inch grapple on a CUT. The 60" would probably work better IMO and if they had a 48 inch version with a single upper jaw they would give Gator a run for their money.
Again, welcome to TBN.