I considered the brush guard when I bought my X500. But I really like the way the front looks and decided against it at the end. Plus I heard the brush guard was pretty cheaply made and bends very easily.
I have a brush guard on my X304 as you can see in my avatar. I like it. I have ran through my cedar fence with it twice, long story, don't ask, and it didn't even get scratched, and it completely protected the hood.
Here is a couple pics. You need to pull the pin and then a rod out before the hood will raise. It is built plenty well for a "brush" guard but as in "all" JD extras it is over priced. :fing32: "Click Image For Larger Version"
Here is a pic of my X300 with brushguard which is the same for the X5xx's. Today I got my tractor stuck and at one point while trying to get it out the tractor rolled down a little and went right into a utility pole. The entire weight of the tractor was on one side of the brushguard pushing into the pole and the guard held up fine. After that I got my wife to drive the tractor in reverse while I pushed.