MustEatBrains:
There are other races with statistically rare uber-kills already (Dilgar Bolter Crits, pak'ma'ra Plasma Torpedo crits, Heavy Missile Volleys) that, while spectacular, aren't overwhelmingly unbalancing innately, because the averages are right (and, yes, I know your objection to this thought process, Ripple --- duly noted.)
What we are, I think, really debating is how much this is a beer-and-pretzel dice rolling contest, and how much it is a serious strategy grind-it-out. As have been previously mentioned, if the balance is right --- and, given that we don't have the rebalanced ships, we can't even begin to guess or second guess this, we'll have to accept it a priori, we are talking about different methods, within the 1d6 system, to give the same balance (average yield), while fine-tuning the standard deviation (how much is luck vs. skill). The values are all very close, we're just witnessing three similar options, in ascending standard deviation:
Jim's Beam Mechanic: Always start with 3, use the current beam rolling rules (beams overpowered by 10% here.)
Triggy's Cap: Cap the number of sustained hits to 4 (beams underpowered by 6% here)
Current 2e: Beams neither underpowered or overpowered, but immensely luck-dependent.
What we're debating is standard deviation; or, how much do we want this game to be about luck, and how much about skill? We may not be the best audience for debating this, as we here are all pretty hardcore tacticians; but I personally do prefer a game of skill (Jim's mechanic) best.