To add to Neil's point, if you have a tendency to have lots of "junk in the trunk", like 'roll bars' and dinghy + davits an outboard, etc...those 150 lbs of battery might help offset the stern weight.
Anyway, I decided to make my two settee tanks water since they are often full, and made my holding tank the bow tank (my boat only had the one little 17 gal tank to stbd) since I only fill the holding tank when necessary so it always starts a journey empty. It all makes a difference, but on big heavy boats like a C-30 weight distribution probably makes less difference than some others.