Wow, wasn't expecting this much of a response...

As I said above, the fact that the CRF and DD are currently interacting makes all of my observations suspect; and any objections I raise might pale in comparison to imbalances we haven't yet discovered because e.g. the DD and the UGCR decided to work together instead of butting heads. So, take everything with a grain of salt.
The way I see it now, the DD encourages turtley / defensive / time-buying play, to allow for the ecoomic bonus granted by the supercomputers and the high-tier projects to come into effect. It's meant to snowball into the lategame, and the early stats of the fleets reflect that: we get one of the most cost-effective shield-to-command-point ratios (heavy cruisers!), allowing us to play defensively and regen some of our lost health between tactical engagements, and we have a very solid range advantage over the other nations' fleets (artillery). At game start, however, our fleets are considerably weaker than our opponents' (low potential) and in the actual game, we will also start with a resource disadvantage. Furthermore, artillery @ range 3 has a very lackluster damage output and artillery fleets are very squishy.
The way I see it, this means you
need to be able to hold enemies off as the DD; and this lack of hitting power during the early game
needs to be offset by good late-game power, to balance things out. Now, consider the projects the DD has to offer (all of the following information can be gleaned from previous turnsheets, so I'm not divulging anything horrible):
Tier 2: Supercomps (2000/2000): Tier-for-tier, best project for the DD. I have
no complaints about this. Best value-for-money we've had so far, and, in all honesty, this might need a nerf. Consder, however, that this allows the DD to economise MONEY, not RESOURCES; as such, resources are worth as much to the DD as they are to everyone else. Keep that in mind for the following projects, please.
Tier 3: Phase torps (1000/4000 for research, 0/1000 per shot, one shot per fleet per turn). Huge upfront cost, especially given that most of it is resource-based (4k resources is a lot). I, of course, acknowledge that other factions' projects probably have similar costs and am not crying imba - just pointing out that just making this available to the admirals isn't cheap. Then, of course, you need to spend 1k resources
per shot and you are limited to only one shot per fleet per turn. Thankfully no refit is required to install this.
As niffiwan pointed out, this is only cost-effective when firing on more than one targets (you need at least 2 centres and 3 flanks as targets to cause cost-efficient damage). Furthermore, 10% damage across the board does
not affect the damage output of the enemy fleet, unless you knock them under 50% (an 80% fleet does exactly the same amount of damage as a 100% fleet and is, therefore, equally dangerous in a tactical scrap). Furthermore, phase missiles hurt
all fleets in a location, so they can't be fired in a melee, unless you are willing to suffer equal losses;
and they can be blocked by inhibitors, so a sacrificial fleet can hold off the fire of an entire DD 3-fleet armada if it's willing to take a beating to protect the rest the invading force. Finally, there's the matter of action economy: admirals
need to spend their first action to guarantee a hit. This takes a toll on DD fleet mobility.
i.e. your only chance to score kills (or seriously inconvenience an enemy) with phase missiles is to keep up a steady fire of them and pile on the damage, turn after turn. And the enemy needs to oblige you, by staying there and taking it.
Tier 4(a): Fleet modernisation (1000/3000): Adds 2 max potential, 10 shields to flanks and 15 shields to centres. Requires free refit. Probably comparable to 'speed doctrine' and other projects that add flat numbers to fleets' stats. I'd like to know what the cost of such projects is for others; note that modernising requires a free refit, which requires retreating / burning actions to get a small bonus. Frankly, I have no idea how significant this shield bonus is (it's equivalent to just 1 primary weapons hit or so), but the potential unlock is important, I think. Again, HEAVY resource cost.
Tier 4(b): Undying Loyalty(2000/0): Adds one morale to all, immediately. I like this, because it focuses on money, and rewards you for your earlier investment in supercomps. No objection here; again, some small nerf might be considered.
Orpheus, this answers your question.Note that NONE of the above projects gives you additional options in a tactical environment (where the actual damage to enemy fleets takes place), only small buffs to fleet stats via modernisation / morale. The DD starts with its main tactical advantage (peashooters with range); and other factions acquire skills that counter this advantage in the early/mid-game (T3). Mirage fields (that make artillery miss) and Valor (which closes the range to enemy artillery and supersedes the artillery firing order) are, essentially, hard-counters. The only additional tactical order that the DD gets is T5 (so,
very lategame, I'd think) and it is, again, a range-based order, with some pretty heavy drawbacks for the DD. Also, heavy in resource cost (ugh) but, thankfully, no refit required. Can't say anything else at this point, and it remains to see how it's going to work, but I'm not very convinced.
Add to this that the latest CRF project appears to hard-counter our phase missiles, and you can understand why I'm attacking walls with my head. The CRF can now repair damage in 20% blocks, without a supply line or repair facility and with no (apparent) additional cost. They can also do it without the admiral burning repair orders - and they can do it
in combat as well. So, essentially, they can keep their fleets moving, all the time, provided they have enough resources to throw at the problem. The piddly 10%/20% damage that the DD fleets can inflict with phase torps can get instantly repaired next tactical turn, even if the DD fleets follow their phase missile launch up with jumping in and engaging in a tactical fight. What's the point of softening up your opponents when they can immediately repair the damage they suffered before you follow up? And hasn't something gone horribly wrong when the enemy can repair better than you while in orbit over your besieged planet?
(BTW, Spoon, can an admiral give the repair / refit order while in combat?)
And if the argument is 'outspend the enemy', then I'd like to remind you that the DD can economise
money with the supercomps, but we are as dependent on resources as everybody else. 1k resources spent for your enemy to spend 400 money and 700 resources to immediately repair is, arguably,
not a good deal.