It was ok depending on what you used it for. The biggest issue I had was dropping wood out of a loader into it and cracking it. I put extra supports on there so it went to 6" on center instead of 12", and I never broke a piece after that. I use the truck primarily for wood, though I ran stone, stone dust, gravel, sand/salt, and various other materials from time to time. If you were constantly running large rocks, it might gouge it, but for the couple years I had it on there before I sold the truck, it held up pretty well.
I designed that dump myself, and it went up to 70 degrees when it was up all the way. That and the trex, never had a problem with anything ever sticking in it. My new truck only goes to 45, and I wish I had the extra lift.
If I had to buy the trex brand new, I probably wouldn't use it, but my dad had some left over from a deck project, so I got enough to do the truck for free. I will be redoing my flatbed soon, and I'm planning on using 1.5" oak planking.
2002 Chevy 2500HD flatbed
LB7 Duramax Diesel
Meyer 8.5 V2
SOLD: 1998 Chevy 2500 with rear airbags
Western Unimount with wings
Meyer 2 yard V box