Sorry, I didn't mean to come off as rude.
I've just seen a number beds that I considered ruined by those drop-ins. One example is a little Ranger I had for a while that came with a factory liner. Looked pretty good but the liner was bowing (sun?) and looked bad. When I took it out you could see major rust damage in many places (dozens to be very conservative) where the liner had chafed away the paint.
I hope yours works well for you, but for me, they are not even an option to consider. Well, maybe if I had a beat bed that was all beat up dented and rusty to start with that I just wanted to make look better economically?
Then again, my experience with the spray and roll on liners seems diametrically opposed to others posting, so who knows why such a different range of experiences. <shrug>