I think the only advantage to the drop-in
liner is protection from dents in the bed. In most other respects a spray-in
liner wins.
Rhino is thick, rubbery, and tough. Line-X, Arma, Magna, whatever else, are thin, hard, and tough. The choice is a matter of personal preference.
The shop that does the job needs to do things right. Take a look at the work they've been doing. Ask the different shops how they prep the bed. Check the guarantee. Is it nation wide or is it only with that particular franchisee?
Ken