I used raptor liner and I'm really happy with it, but I will say that it's pretty hard to clean mud out of it. From my experience with line-x (had a trailer done with it) it's extremely coarse, even enough to scrape yourself on. That being said, raptor liner is a lot smoother, but it does have texture still, so it'll be hard to clean mud out of it still. Stuff like sand is much easier to deal with though.
Here's how mine came out. It's a lot of prep work involved if you want to get a nice coat that'll stand up to abuse. Basic list of steps involved with what I did: scrape up that sound deadening gunk, take a wire wheel to the rest of the left over gunk you couldn't scrape up, sand down the entire body, wipe down with mineral spirits, tape off everything you don't want sprayed, including grounding points and filling bolt holes with something.
Some more info and pictures in this post I made a way back:
http://wayalife.com/showthread.php?14866-Lining-the-inside-of-the-tub&p=255437&viewfull=1#post255437