Live Rock: Weight VS Surface Area

[cd5]

First time I have every posted, I mostly enjoy reading old forums questions, here is my question, If i am looking for pieces of live rock in lfs, are rocks the same size yet lighter(more porous) just as good as heavier same size pieces, does the weight of the rock actually help biologically or can I just look at surface area of live rock
PS: Have learned a lot from this site

 

[frshwaterfinatc]

Welcome to Aquarium Advice!

 

[bound_for_obx]

More porous = More surface area = Better... I think.
Plus, if you're paying by the pound, it costs less! 8)

 

[Atari]

Lighter should equal more porous, so yeah better for filtration. Usually the lighter types are more expensive to balance it out, but if it's the same price at your LFS then go for it.