Well it depends on what you are using the car for. Between seats,wheels, battery, and miscellaneous items, I have saved 200 pounds, and it has come from all parts of the car. To flatly state that weight should not be removed because it is from a particular side of the car is a little too narrow in my view. Plus, 35 pounds can easily be compensated for by a small adjustment in corner balance. Perfect 50-50 is not going to be as significant in my view as a lighter car that is, say 49.5%-50.5%.
I would not get the battery for daily driving, but I would get it as part of a comprehensive weight reduction plan.
FS: Leather Recaro Pole Position Seats & Hardware