If you grapple brush long enough, especially if you are doing more than simply moving piles around, eventually some "stick" will find its way to either tear a hose, pop off a coupling or knock a lever.
In about eight years of pretty aggressive grapple use, I've had one hose damaged. My Millonzi grapple has zero protection for hoses or cylinder. While driving the grapple into some brush, a stick wedged itself up around the cylinder and snagged the hose right were the JIC fitting enters the cylinder. It bent the hose it so that it leaked from the hose/fitting junction. No biggie to replace (although I had to do it twice as I cracked the first replacement when I installed it-- never knew before that JIC fittings should only be tightened gently, unlike SAE fittings).
A grill guard and grapple cylinder guard are certainly useful and having the hoses long enough to have a bit of slack/give (controlled with a bungee to keep them out of the way) can help too. However, nobody should be shocked if a particularly vicious stick manages to evade your defenses. Part of the cost of doing grapple business.
