I've had Line-X over the rail for a little over a year. I did the Line-X Xtra UV protection which makes the finish glossy black - not semi- or flat like the regular liner. The Xtra makes it a little harder and takes away some of the impact qualities, so have them spray it a little thicker if you go that way. The Xtra keeps it from fading over time. Of course, I've also had a SnugTop shell sitting over it, so the fading thing for me is a moot point until I take off the shell.
I gouged it ever so slightly yanking a heavy jet ski out of the bed with only one other guy - not the liner's fault. I've had Rhino and will say with certainty that the Line-X is far tougher.
__________________
2007.5 Ram 2500 MegaCab 4x4, 6.7L, 68RFE, 3.73 gears, SLT, Line-X, Snugtop Extra Vision shell, Bilstein 5100s, 285/75-17 Toyos, Walker Evans wheels, Amsoil lube & bypass filter, PML rear diff cover & tranny pan, Dynatrac Free-Spin, Arab's kid's college fund