The weight for these seems to be inline with much of the aluminum market. I don't own aluminum but in looking at them it seems both are within a tolerable range of each other...

The Pelican luggage appears to be rigid unlike what they are calling hardside today. The suitcase doesn't have to be full before it gets support in the middle of the panel similar to aluminum or the "old" hardside luggage. I have a hardside suitcase from about 10 years ago that my wife uses when we go on vacation that we will need to replace sometime. It is still functional (and has taken a beating on many trips) but starting to look around for a replacement.