I had rhino liner applied to the plywood floor of my cargo trailer. it is HEAVY!! rhinoliner is more flexible than LineX. It has worked great as a floor in my trailer, but from my experience I wouldn't even think about using it on the roof unless they have reformulated it considerably for roof applications. The reason is that even with good prep, it doesn't stick to plywood near as well as it does to metal. And it does have a tendency to develop small cracks when if flexes. I'd be concerned that it wouldn't make a good long term seal over the roof decking and trying to get anything to stick to it along any edge seams could be very hard. I haven't found anything that will stick to the rhinolining on my trailer floor when I tried to seal the edges as they wrapped up onto the walls. Silicone, dicor, eternabond, sitkaflex (sp?) will peel right up.
Now if they have reformulated for roof applications it may be a completely different story.
2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!