Ford's "600~700" LB weight reduction is based on the new aluminum bed equipped trucks with the V6 Eco-boost engine vs. the previous steel bed model with a V8. A lot of that weight reduction comes from the lighter engine rather than the aluminum body / bed parts alone.
With the weight reduction, Ford F-150 is lighter than the competition, but only by a maximum of less than 100 lbs. (Extended Cab 2WD base engine for comparisons)
F-150 4912 lbs
RAM 1500 4989 lbs
Chevrolet Silverado 1500 4982 lbs
I generally don't like plastic bed liners due to their propensity to collect and store moisture. F-150 of course won't have a rust problem with the truck bed but it can cause rust on cargo and accessories like tools. Also even though aluminum doesn't rust, it's not corrosion free, and environmental compounds in air are water soluble.
I much prefer spray-on bedliners, and they are available from the factory when you buy the truck. With regard to paint and finish in general, there is no way you can come close to a factory finish cost wise at an auto-body shop. Premium paint, even on some rather pricey automobiles, is quite inexpensive (usually less than $1000, I've seen $400 on some). One of the best bargains on the option sheet, as it also raises resale value, sometimes by the same amount or more than you paid. Not a common situation with options.
As usual, you have to make your choices based on your own requirements and of course if you have a brand loyalty, you probably are going to pre-select a vehicle based on that.
