This was the topic of conversation during a recent SO training course at Sig. Due to the proximity of residences and other structures around the academy, during their events, they will "comment" on keeping the muzzle at or below the berms which are fairly substantial. They have a perfect safety record since they opened years back and they aren't looking to ruin that. Simply looking at the ceiling of the indoor range will tell you shots can and do go high.
But on the other hand, i myself favor the muzzle high reload and it has been advocated by more than a few instructors for high speed reloads during competition and the real world.I frequently used it during FI quals over the years. As far as a revolver, it's pretty much mandatory.