I couldn't say on most of this, and I'm a Glockster to boot. Thing is...the magazine is in your hand when you are shooting. It may be covered by the grip and all, but it's where no difference in weight should be of any issue with balance of the pistol as a whole. The weight of a fully loaded magazine compared to a near empty magazine should not affect the "balance" of a pistol if good engineering is involved. (period). I do shoot competitively at least once a month with my Glocks. Only change in accuracy would be affected by me and not a fully loaded or near empty magazine. It has to be in the design rather than user adaptability. Doesn't it?