The balance you require is "Lateral balance".

Yes, you shoud do it.

Your wings generate lift in proportion to wing-speed, and angle of attack. If one wing is heavier then the other, you will have to geenrate more lift on the heavy side to support the wing in "straight-and-level" flight (normally by "trimming" the ailerons).

If you were to do a loop with a trimmed, but unbalanced plane, then the lift forces of each wing will remain equal, but because the heavy wing is heavier, Newton;s laws stipulate that the heavy wing will take longer to do the loop... F = Ma (Force = Lift, M = wing mass, A = "how quickly wing lifts in loop")... The heavier wing has less accelleration ...

What happens in practice is that the plane will not "track" evenly through the loop.

This is evident in more places than just loops, but is easier to explain that way.

Basically, a laterally balanced plane will behave more consistently than an unbalanced one.

gus