I've heard about the balance issues before. The way I heard it, when the aircraft had a full load of fuel, the balance (and center of gravity) was right, but as fuel was used in flight, it became less responsive and the balance was off. For most flights nowadays, the tanks wouldn't be totally full; only enough for whatever show or whatever flight was needed.
On the other hand, the fabulous P-51 had a similar fault, but in reverse. It had a rather large fuel tank right behind the pilot in the fuselage. When the plane was totally full of fuel, for the long escort missions, it handled terribly. However, the pilots soon learned to switch the fuel draw to that tank FIRST, so that tank was used first and the plane became much more responsive and the CG and balance was right.