I personally felt the I24 changes would make him slighty overpowered. (Not that I wasn't stoked for them)
There was no time in the existence of the game that any archetype wasn't overpowered relative to the game's balance standard for players with sufficient dedication to maximal slotting and optimal gameplay.
The game wasn't designed to be balanced around maximal slotting and optimal gameplay. It was designed around the median player performance, as determined by watching all the players who played the game and measuring their median performance. Under that metric, there was never a single moment in the existence of the game where blasters as an archetype were not severely underperforming all other archetypes. We're talking 25%-50% underperformance.
That's not 25%-50% under the other archetypes. That's 25%-50% under the median performance: many archetypes were over the median performance, which made the gap between blasters and the higher performing archetypes (i.e. scrappers) higher than that. The single largest contributor to this underperformance was that blasters were dying at a far higher rate than all other archetypes. Solo, teamed, low level, intermediate level, high level, max level. In all types of content. The numbers say that if you think you were doing well on a blaster, there were ten players doing just as well on every other archetype and a hundred players doing vastly worse on blasters. If you didn't see this, your experience was not representative of the playerbase as a whole.
The truth is, nobody cares about min/maxers or the power gaming elite, nor should they. The developers didn't need to care about us. We could always excel under any circumstances. The devs cared about the typical player, because those were the ones that kept the lights on. They represented the bulk of the players, the bulk of the playing time, and the bulk of the subscription revenue. They needed the game to present a roughly level playing field to them, and that's ultimately where the devs spent most of their energy. And I would have eviscerated them if they hadn't.
My calculations suggested that in broad strokes, I24 blasters when played by the average player would probably be in the general vicinity of I23 median performance in solo play during leveling conditions. Slightly under on average, but close enough. My worry was that the collateral buffs on archetypes like defenders and corruptors would increase the median performance enough to where blasters would fall below the median again. But I think at least for the average player, blasters would start to become competitive with scrappers as offensively focused characters.
The people already farming +2x8 with blasters? The I24 buffs would have less of an impact on them relative to average players in most cases, because those players were already reaching saturation levels of power that small to moderate buffs have more difficulty improving. And if they did, small price to pay to improve things for the other 95% of players. The same thing happened with the invention system. It let the 5% become far more powerful, but it also lifted most of the other 95% to moderate levels of performance far more consistent with the newer balance standard for players post-I5 (particularly when it came to soloing).