How much oil goes into teh V8 vs the V6? maybe a quart diff?
Does the insurance company see a diff?
My friend's wife traded in their '05 V8 for an '07 V6 Runner and she gets almost 3 more mpgs around town with the 6.
Unless you're towing I don't see the big deal with the V8 unless you have to beat that V6 in the 1/4 mile. ;)
I'd probably have to have the V8 just because.