For a long time, my group kept treating plasma weapons as the redhead stepchildren of Imperial tech.
In Dark Heresy, they were plain awful - damage barely better than bolt weapons, Overheats, Recharge and damn expensive? Pass.
In RT, they got somewhat better, but Bolters were still better thanks to Tearing and Full Auto capability. I remember my Rogue Trader being quite fond of his standard issue plasma pistol, but he barely used it at all and when he did, he didn't exactly outshine anyone.
In DW, they were downright worse than Bolters. True, they had a slightly better minimal damage and better penetration, and they triggered Righteous Fury without a confirmation roll, but they had a much smaller chance of triggering Righteous Fury in the first place when they rolled one die for damage vs three dice of the bolter.
Finally, in DW errata, plasma weapons became quite awesome, with a much better damage output and penetration. And they even came in full-auto variants!
But the real game changer was in Black Crusade. The new wording of the Overheats special rule made it extremely dangerous to use, and Zealous Hatred made Volatile obsolete. Still, the damage was godly, even before Maximal setting, and the new rules on firing modes made the lack of full auto a mixed blessing rather than obvious suck it meant before.
All in all, I liked the BC plasma the most. It was powerful enough that you wanted it, yet dangerous enough to give you second thoughts, at least until you could afford it in best craftsmanship. It was fun, it was more or less consistent with the setting lore, and like most new weapon rules in BC, it made plasma weapons into an interesting choice rather than a must-have upgrade.
Therefore, I'm very unhappy that in OW, Plasma Weapons more or less returned to their RT state - the damage got nerfed back, and the old Overheat returned, making it more of a nuisance than a real threat. Since OW uses the same burst fire rules as BC, the lack of full auto is not the kind of problem it was in RT, but that's seriously the only thing that remained from the awesomeness that plasma was in BC.
My squad is not likely to get plasma weapons any time soon, but I'm inclined to change them back to their BC state, both in statline and in how Overheat works. What do you think?