I can see people logic on wanting to balance with a half tank. What people fail to relies is this has been accounted for in the design. Follow the directions and balance the model empty. And do this with any model you own. People that are telling you to balance with a half tank is simple spreading their own BS thought process.
When in doubt always follow the manufacturer


If and when your worried about fuel effecting flight performance, I wouldn't worries about this except in compitition pattern or 428 racing, then get a bladder fuel tank and a pump relocate the tank to the CG point and rebalance the model. In this case you may want to move to the rear of the CG recommendations to compisate for the fuel not being there, you would do this becuase your not going by the manufacures build spects which would need to be altered, also before you alter the CG point flie it stock first then make an adjustment