2 lbs/gal is a bit extreme, IMHO, altho that's the rule if the LR in question is pretty dense.
to be honest, i never really know how much LR i put into a given system. i aquascape it until i'm happy with it and however much that is, is how i roll. in fact, my SH setup looks fairly sparse in terms of LR (it's mostly Tonga branch), but it's well-planted with live macro (which i feel is almost a "must"), and half of the sump contains LR as well.