I really could be way off here, but from the little that I have seen, it would make sense progression wise and also placate many of the people that think Laser I-V is a boring way to do the techs.
Even something as simple as Light Laser, Medium Laser, Gattling Laser and Heavy Laser would be a big improvement.
Along that idea is to have the first tech be Lasers and then have the next 4 techs change what the weapon can do. Make it the 1 point smaller, but then also add in the option of MoO2 style weapon modding (Auto-fire, Continuous, Heavy, Point-defense were some of them for beams). I know in MoO2 the mods changed the size and cost of the weapon system, so you can either keep your 1 damage laser that takes up, say 5 space instead of 6, or you can make it a heavy laser that does 2 damage, takes up 6 space and adds x% to the cost. I'll be honest that I can't see how well that it would balance, thought the ability to have some very heavy weaponry that is almost to the point of prohibitively expensive would make it somewhat self balancing (there is only so much point in making a fighter that has 6 attack early in the game if it takes 15 turns to build each one).
As for navigating\adding techs to the tree, it could be made possible for the tree to be something like:
Galactic Warfare--Beam Weapons--Lasers----Plama Cannons----Phasors
..................................................................|-Heavy............ |-Heavy............... |-Heavy
..................................................................|-Continuous... |-Continuous... |-Continuous
..................................................................|-Autofire......... |-Autofire............ |-Autofire
To prevent people from just going straight through the tree, maybe link the starting tech cost of the main tech (I.E. Plasma Cannons) to the other techs researched under Lasers. The more of the Laser weapon mods you research, the lower the starting price is for plasma cannons, as you are getting a much better understanding of the physics of Lasers and are coming up with ways to move beyond them.
Now, I am not saying 'Do it this way!' If people don't think this would be a reasonable way to do weapons, especially frogboy and the rest of the Devs, then it wont happen.
The thing that I am not sure on, except for heavy, is what the names\functions for all the mods would or could be. Heavy, as the name implies, could be an over powered laser. While it isn't much bigger it is far more expensive for durable focusing lenses, etc. Maybe Autofire has a chance not to waste its shot on an already destroyed vessel (Make Huge vessels useful against the mobs of tiny hulls, while not guaranteeing that 1 huge ship crushes fleet after fleet). Maybe Continuos has a small chance to also inflict damage on the next target or a few extra points on the current target if it hasn't blown up. These things I just made up as I went along in this post, so people can get much more elaborate and creative (also opens the door to user created weapon mods)
And lastly, I really didn't want to write this much, but I got going....and well, might as well spill the whole idea out there. I hope that you guys don't think this is too far fetched an idea. If it is a little too far out for the expansion (as it would also require changing some of the combat code and AI code) I hope that it would be considered in a future sequel or for another game that would be applicable.
Thanks for reading.
GalCiv2 Forums
Hopefully some form of it could be considered, though it may be a bit too much change in the combat dynamics to implement.