Aluminum will hold up just fine to a point. Like DT86 said, you can scratch it. Mostly though, just taking a little care to place your load or throwing a piece of plywood down first for something really nasty and you will be fine.
If you get a bed with a rub rail, be careful if the rail gets pushed in. If you try to pry out a dented rub rail, place clamps over the rail where it is welded to the stake pockets. Those rails take a lot of pulling with nylon straps. Take a crow bar to a dent and the weld can pop right off the stake pocket.
Which does bring up a point. Straps with J-hooks are more friendly to the aluminum then chains. Also, look for standard sized stake pockets. Eby for one makes a smaller stake pocket. Stock J-hooks will not fit in the pocket without squeezing them in a vise.
Brite aluminum is easily dulled out with strong cleaning agents. I don't know the grades but the more "standard" aluminum will oxidize and standard washing will not bring it back. You can find places that will "acid wash" the bed to really clean it up. It is going to look "white" but won't really ever shine again if it ever did.
Overall, I think it is kind of a "wash", aluminum over steel. For a small truck application, I do not see a big savings in weight. Brite aluminum is going to require a lot of cleaning to keep it looking brite. A regular aluminum bed will over time dull out but will be somewhat "presentable" with occasional maintenance. A steel bed requires regular touching up with paint to repair the scratches. I have had both and everytime I loaded something on my steel bed, I would scratch it. Screw ups are an easy fix on the steel bed. The aluminum maybe not so depending on your local welding resources. A steel bed with piano hinges for storage boxes or a gooseneck hitch cover will rust and be hard to keep looking good.
A lot of beds have a simple flat plate that folds over to cover the gooseneck ball if you have one. Eby for one makes a nice cantileverd cover that holds up well.
Lastly, I had a steel transfer tank on my aluminum bed for several years. I placed a piece of rubber horse stall mat under the tank rather than bolt the tank directly to the bed. The mat I used had ~1/8" grooves on the back side. As I said, I place those up. I figured the air space would preserve the steel which it did. When I did remove the tank, the aluminum had not oxidized under the rubber at all.
I say, go with the look that you want. Hope this helps.
