Even with a longer draw length I have shot at 5 grains per pound in the past for extended periods of time with no apparent damage to the bow. As Rangeball briefly commented on, I think it would depend on a variety of factors.

For example, I wouldn't go shooting an lower price bow with inexpensive components at 5 grains per pound (70 lb draw weight) when my draw length was 32 inches...<img src=icon_smile_wink.gif border=0 align=middle>