Before, Kinetics were almost twice the weight of Lasers. Now the tier 1 has idenitical weight as missiles, and never goes up as tiers increase. By the end of the tree, Singularity Drivers are the lightest weapons in the game, equal to Doom Rays, which is fantastic, since doom rays are extremely light.
Durantium weapons still aren't changed, however, so their weight is still massive, but so is their power, making it justified. I also think this is good, as super-light Durantium weapons would be insanely overpowered, given how common Durantium is.
I think they might finally be balanced. We'll see, but so far things are definitely looking up for balance.