I would say that the optical would use some more juice since it has to power the LED's which are quite powerful (in my Logitech iFeel Mouseman that is). The only place though where this could be an issue would be with notebooks and in cordless battery mice.
How much do you think it would affect the battery life of a notebook and in cordless mice.
How much do you think it would affect the battery life of a notebook and in cordless mice.