I would go with a drop in unless you want to have problems in the future. In some states (and coming soon as a Federal law near you if EPA has it's way) all pickup beds with spray in liners will have to be disposed in an "environmentally friendly way". What this means is all beds with oil based spray in liners will need to be separated from the vehicle when eventually junked. What this means is expense to the owner. Expense to you in the form of lower resale as this expense is figured into vehicle lifecycle costs as used buyers won't want the future liability. Don't forget extra expense to insurance companies on totaled vehicles which means, more expense to you to insure. Since nobody to my knowledge has figured out a way to produce a durable, water based spray in liner, these laws will eventually spell doom for the spray in industry.
