I recently sold a Diamondback 270 cover with the Line-X coating. Had it on 2 different trucks since 2014. Quick rundown of 6 years of using the cover:
+access from 3 different panels is handy
+gas hinges are indestructible
+quiet, once you adjust it properly
+looks bad@ss compared to most covers
+very light, easy to take off and put on
+locks up tight like Fort Knox
+more adaptable to various trucks than other covers
+holds value decent, used 6 yrs. sold $500
-have to adjust regularly for rattle
-weather/dust proofing isn't awesome
-Line-X didn't hold up well in AZ sun
-if you don't remove panels at EXACT correct angle, you will break the hinge flanges
Just my $.02!