I never noticed a problem with the CG on the factory marks. The plane balanced spot-on with no battery, and the battery is centered under the CG. I used two GWS Naro servos, and a Mini for the ailerons. Even balanced on the "tail heavy" factory CG, the plane is not twitchy on the elevator.

Many people don't like the standard GWS battery mounting system, so it's not unheard of to hog out your own battery bay. Definitely not something that would attract the attention of the GWS Battery Bay Police, that's for sure