There are 3 "levels" of bedliner coating...
Single Component (Durabak, Herculiner, etc). Price is less than $100.
2 Component (SEM, Gator Guard, etc). Best applied with a Schutz (undercoating) gun. About $100 - $175.
High Heat, 2 component (Rhino Liner, Line X). Must be applied professionally because of equiptment. Cost is several hundred dollars.
2 component urethane coatings will perform better (adhesion, durability, etc) than single component coatings. High Heat systems will outperform 2 component DIY systems. Depends on what you want to spend.
Prep is critical. Sandblasted metal with a 2 component urethane primer would give you the best mechanical / chemical adhesion for DIY systems. (There are better coatings for this than POR).
I blasted to bare metal, sprayed a 2 component urethane primer, then followed up with SEM 2 component bedliner applied with an undercoating gun for a consistent film build to 3/16". No delamination, it's not 'sharp' because it doesn't have rubber bits, been satisfied so far. Cost was about $200 including the primer.
The extra money was well worth it, but this is all just my opinion (but backed by my former cube mate who is an automotive paint engineer).