Belt sander speeds

What are your thoughts on sanding belt speeds for an RV build? I have read that for sanding metals (including aluminum) faster is better. I've also read that in general, speeds from 4000-8000 SFPM are recommended for mild steels and aluminum. I believe that using faster speeds and a light touch will produce a better finish on the aluminum and that coarse grit paper will produce smoother results at the faster speeds. I think the faster speeds also help the grit to wear down better. It seems that most of the models sold at home depot and the like are meant for wood and therefore have slower SFPM speeds, in the 2000-3000 range. I think for many people, belt sanders boil down to the best bang for the buck (i.e. cheaper models), but I'm not opposed to spending the money for good quality tools and getting what is needed.

Thanks,