Standard HBG (BG x GSF ) are more aggressive but there is serious question if they grow faster for any significant time. But remember that a direct comparison of populations of BG and HBG is misleading as 90+ % of the HBG are male. A true comparison would be against a population of BG that were 90% male. In that event the size difference would be minimal.

There are studies on aggressiveness and HBG are more so than either parental species. This leads to the warning that they can easily be fished out of a pond.

The stunting of either BG or LMB is a question of balance (population dynamics) between the two and/or other species in the pond. If either species is significantly out of balance expect them to stunt over time unless the imbalance is removed or greatly reduced.