It's not as porous as the imported live rock, but it's easy to use as a base to aquascape. I wouldn't rely on it for biological filtration. As for it's mineral composition, it's fine.
Oh I'm not replacing LR at all just adding these guys in. I know these aren't porous enough for any type of bio-filtration, but the addition of minerals i.e. CA, Mag, and stabilzing my PH and dkh, I think it maybe worth a shot.