I have had 1/2" HDPE on my Puma decks for over 10 years - it has never cracked; the only issue was some sagging, as the frame does not have cross bars, so I had to put in some aluminum support straps. However, I just put a large deck on the front of my 16' Hyside - went with the 3/4" and it is supported by the frame on all 4 sides. I got "starboard" which is the marine version for UV exposure and it has more texture than some. Routed slots for straps and attachment points and beveled the edges - it looks great, no maintenance and I am very happy with it so far. It is heavy compared to wood, but really, in the big picture it's negligible compared to dryboxes, cooler, etc.