I find the weapon split to be completely pointless as it stands. Here's why:
Missiles rule all. At least at the lower tech, and I've never played a game where anything past tier 2 weapons were deployed so for.
Why do missiles rule? Simple: Each unit of missiles is twice as strong as the other weapon types. But defenses are the same, regardless. Meaning that Missiles pack twice the punch, making them twice as good in all circumstances.
What's this lead to? Watch out as I pack as many missile components on all my war ships. Which, incidentally, are always small. Why? Missile armed fighters (fighter swarms) rule all, at all times. Why? Because you can pack more missiles into a unit of small ships to form a combat unit (fleet) out of then any other hull types.
What's this mean? The AI gets into point defense. Very heavy. Indeed, it is not uncommon to see the AI building medium ships with a big beam 1 attack and point defense of 14 (with us all at just the start of tier 2 weaponry, but the AI heavily invested in Missile Defense as hard as it can) in most of my games. Do you know what happens? My fleets of fighter swarms always triumph--- because they are packing 2, sometimes 3, missile components on each hull, and my swarms of small maxxed missile fighters number 3 or 4 units each (sometimes 5, in the later stages). Eats the AI alive. 14 PD doesn't protect much against repeated 6 points missile attacks so that after just a few hits, the PD cruiser is destroyed, while the fighters small small hull *can* take the same number of hits from their weapon. Power balance: Missile figher swarm.
The AI, however, is completely immune to itself at that point, because its researched missile defense and put it so strongly onto its ships. Remember, defense counts for 1/2 against the other type of weaponry. So all those max PD ships its built cannot hurt each other. But I wipe the galaxy of the AI, and conquer as fast as I can ship out the troopers.
VERY boring. GC1 offered more challenge, racing to battleships and AMM. Unlike GC2, where the Missile Swarm is good from the very first turn after you have researched missile tech.
If Missiles were reduced from being TWICE as good as the other weapons, then I'd just do the same thing. The only real effect of using 1 rating weapons is that you have to make a lot more replacements. But still not a bit of real challenge because there is *zero* R-P-S system in the current set up.
I was hoping the latest AI would do better at defeating fighter swarms, but it doesn't. The problem is the balance between weapons and defense. Defense just isn't worth wasting time on for the first few cycles of warfare tech. Putting defense on a ship is a waste of space that would be better served putting in, by priority/best useage: a) another weapon of the same type as already on the bird;

engines (improves getting the first shot); or, lastly, c) sensors (seeing your target).
Right now, defense is absolutely worthless. "Strike firstest with the mostest weapon points" will always win in GC2. It takes too much defense to stop an opponent's weapons. Having a bigger hull doesn't grant enough hit points to make up for that. Not with the current game balance. As it stands now, GC2 has the military challenge of a wet noodle. I know Brad will try to improve that, but without changing the current battle system on a very large scale, it just isn't going to happen.
You know, I've thought about how to change the current balance point. But as long as a battle unit (fleet) of fighters can mount more single weapon firepower then their larger brethren at the same logistics level, the balance of the game will always favor the swarm. The balance point is determined by when you can mount enough defense to ignore all incoming attacks--- and that takes a mega, mega amount currently (ie, will very infrequently happen, if ever).
What if we simplified defense versus attack, so that it could happen? Let's say the game is changed so that so that 1 PD always cancels 1 Missile (of same tech tier), you still end up in an arms race of just sticking more missiles into the same battle unit then your opponent can stick PDs on their individual ships. Again, the most efficent research strategy is to just research the next weapon tech in your choosen weaponry, so that you can fit more missiles into your ships. And with this behavior, you drive all your current and future opponents (ie, ALL THE AI) to either try to get a higher missile tech then you, or race for a tier higher PD then you. Your ships will eat their ships up for snacks if they are trying to play catch up. Ultimately, this means that Brad will have to make the AI pursue missile (and PD) tech with extreme zeal just to keep up-- and that would force all players to go very hard into missiles until there's enough whining about the system that Brad has to make radical changes, or just abandon the whole thing in favor of something else in GC3 (it will take a while to get everyone going single weapon fighter swarm, after all).
Now, I ask you this--- if a single weapon pursuit is *always* better (and it always will be, so long as an attacker has a chance of hitting a defender with that defense), then what's the point of having 3 flavors of weapons? Other then as a special effect on the galactic map/battle viewer?
These are just my experience and ponderings. However, play the available beta to see what I mean. It's better to have 3 fighters with the same weapon then 2 cruisers (medium hulls). It's better to have 2 cruisers (medium hulls) then 1 battleship (large hull). Etc etc etc. The driving determiner is the amount of weapons, not the amount of defense, you can put into that battle unit. Whoever has the most, always wins. Which means--- why bother with defense? The efficent answer is: you won't. If you can stick more weapons on a group of small hulls for your current logistics then larger hulls, then why bother with bigger hulls? The efficent answer is: You won't. If you aren't wasting time researching defenses or bigger hulls, what that mean? You get a weapon and logistics lead. This means, you can mount even more weapons on more small hulls faster then your opponents. Your opponents will be driven to research defense even harder, falling further and further behind on the military power (and the ability to resist military incursions). A very vicious, reinforcing cycle.
Here's a good bet: GC3 will feature a completely different combat system. And the balance between the hulls be very, very great, rather then just a minor bit of hit points and ever less useful construction space. Humm... you know, if they made those changes now to GC2, it could really change the "most efficent" path to be more evenly divided between offence and defence, then you'd end up with more then just one optimal military strategy.