ORIGINAL: cfv007
With retracts I always balance the plane with the gear down. That is the way you come in for landing ... the planes stability most crucial at the time when you are, lower to the ground, powered back, flaps possibly deployed, low airspeed and probably low fuel level ... . this is the time I want no surprises.
The airplane needs to be within the CG range under all possible conditions that you may find yourself in. That means tank empty and gear up assuming the gear swings aft as it does on most single engine fighter types. Your method may work fine 99% of the time but may result in an aft CG condition in the worst case scenario. Just my .02 cents of course.