I think I still have a Word doc containing ships I statted up during the old Starslayer days (ahh the memories), using the Compendium.  Based n that experience, I think that the overall tech level of the Defiance world is easily described by the Starmada mechanics, with the possible exception of phase technology.

The current rules for shields probably work fine to describe how phase shields work in practice, but there are certain navies - the Starslayers and Altai, in particular, with maybe some amaZulu fighters thrown in for the Confederacy - where phase movement might need a bit of thought.

...or maybe the stealth rules that already exist would work... 

First things first: I'll try and dig up some example ships from the depths of my hard drive by this weekend and post them here for comments.

The ships were much easier to find than I thought (I had even made a "Starmada-Starslayer" folder; how prophetic!).

The ship data sheets are made from the online caluclator that then put them in rulebook format, so it may not paste well onto these forums, but here's an example of a Meraxillan ship's stats, with the fluff for all of the ships I'd made copied below:

----
102+40    Crimson Class Cruiser    Shield Rating
Movement Track    1                   
9    8    (6)    5    3    Special Equipment
2                        Armor Plating, 2 Fighter Bays
                       
                       
Weapons    Range
(S/M/L)    To-
Hit
[1] Resonanace Cannons    1-4    5-8    9-12    3+
F    F    FP    FS                             
[2] Cluster Missiles    1-4    5-8    9-12    3+
F    P    S                                  
[3] Proton Missiles    1-6    7-12    13-18    4+
T                                            
Individualized Damage Chart (D6):
Superstructure 3, Weapons 3, Shields 0
Tech Levels (+4):
Engines 0, Shields +1, Weapons +2, Special Equipment +1
----

THE MERAXILLAN SOVEREIGNTY
Still unable to master all but the most basic phase drive technology, the Meraxilla make up for this with their ultra-efficient tensegrity designs.  In terms of overall size, the Meraxillan space fleet rivals even that of the Vobians, though a much higher proportion of its starships are of the smaller classes.  Most recently, the Sovereignty's navy has become more and more dependent on the Geodesic Battlespheres, whose strategic advantages are even more pronounced when fighting Nordic forces far from Meraxillan territory.   

Like their ground forces, Meraxillan space forces are extremely aggressive.  Huge flights of fighters and boarding pods are common, and the Meraxillan Tak Marines are highly selective about who they bring with them from Ulna.  The Sovereignty's weaponry tends to be of the ballistic variety, with both short and long range missiles, rockets and mass drivers, all meant to pound the enemy in a less than subtle (but nevertheless effective) manner.                            
       
Engines Technology Level: 0
Weapons Technology Level: +2
Special Equipment Technology Level: +1

Fighters: Basic or Interceptor
Known for their overwhelming swarm attacks, the Yellowjacket Fighters have been known to take out many a capital ship through sheer force of numbers.  According to Nordic estimates, the first Meraxillan invasion force to cross the Drakor hypergate in AD 1958 contained an almost unbelievable three thousand of these nimble craft.   

Typical Weapons and Equipment: Laser Cannons, Proton Missiles, Blasters, Cluster Missiles, Mass Drivers, Needle Beams, Gamma Ray Projectors, Resonance Cannons, Armor Plating, Cargo Bays, Fighter Bays, Tachyon Detection and Ranging, Electronic Countermeasures, Long Range Sensors, Marines, Boarding Pods, Mines, Energy Leeches, Shockwaves

STARSHIPS

Hornet Class Corvette
With exceptional speed and the ability to lay down incredible amounts of fire, the Hornets are largely limited by their lack of armor and shield-piercing ability, a severe hindrance when attacking capital ships.

Wasp Class Frigate
Outfitted with the powerful Galva Cannons, the Wasp is somewhat slow for a Meraxillan craft.  To compensate for this fact, it carries a small contingent of Yellowjacket fighters to keep the enemy busy.

Expedient Class Cruiser
The workhorse of the Sovereignty space program, the Expedient Class is designed with flexibility in mind.  Expedients can be seen as a part of almost any Meraxillan fleet worthy of mention.

Crimson Class Cruiser
Designed as a highly aggressive attack craft, the Crimsons will often spearhead major offensives, especially those that coincide with a Flux.  Bristling with weaponry, the Crimson's major weakness is a poor point defense system, for which it must compensate by housing several fighter squadrons of its own. 

Geodesic Battlesphere
Beautiful and awe-inspiring, the Battlespheres are wondrous to behold.  Marvels of tensegrity design, they are remarkably cost-efficient for their size.  The sight of a Geodesic Battlesphere signals to the enemy that his position is one for which long-term sacrifice is deemed necessary.

Ah, Jouni, you always catch the little things. 

Actually, that's great, because it reminds me that people don't know wat's in my head unless I write it down.

In this case, I've always imaginged the Meraxilla having phase drive *production capability*, the technology of which was mostly gotten through trading - the phase drive exists on the open galactic market - but without a dedicated phase drive development unit for the government or military.  This is partly due to stubbornness and partly due to the fact that they've mastered other technlogies to such a degree that they are much cheaper.  This is in contrast to the Vobians, who use phase technology in "new and exciting" ways, less worried about the cost (though this has been changing slowly as they have been forced to realize they can't fight everyne else at once anymore).

This philosophical difference is mirrored in the infantry army lists, where the Meraxilla, who *could* give their troops phase fields (I think it's an augmentation), choose not to do so, for logistical and efficiency reasons.  In contrast, the Vobians make due with fewer troops, but each has a relatively speaking enormously expensive personal protection system.

Maybe just an additional -1 to hit a phased ship, as well as an additional -1 for a phased ship to to hit a target?  (cumulative with other modifiers)

Not sure on the passing through objects part, since my Starmada games have rarely involved collisions of objects...

Yeah, the scale of Starmada makes phasing through objects a rare phenomenon; probably only worth modeling in a fighter vs. fighter game.

I was thinking maybe -2 to hit and be hit?  That would be a bit more pronounced.  The idea would be that there would be no counter to this, unlike other ways of imposing penalties on enemy fire.

Hmm, not sure why the post was doubled. [shrug]

I don't think that any current Starmada rules need be "trimmed back" to fit the Defiance universe, which also includes more standard cloaking devices and such.