[AstralWanderer]

Given that SE5 allows variable tonnages for a class based on tech and that models can be scaled to correspond with this, it would seem better to have models and classes linked to roles rather than pure size.

Variations on tonnage would then be dealt with by added a prefix to the class (e.g. Small, Medium, Large, Super, Giant, Titan, Star, Galaxy). An exception could be made for warships where there is a need for a very wide range of sizes and there is a standard list of terms (from both naval terminology and previous SE games).

Military
-Warship (ship-to-ship combat)
--Frigate
--Destroyer
--Cruiser
--Battlecruiser
--Dreadnaught
--Behemoth
--Deathstar
-Defence (fleet defence via PD, shields or armour, repair/resupply)
--Escort
--Defender
--Baseship
-Carrier
-Fighter
--Interceptor (targets other fighters)
--Bomber (targets capital ships)
-Drone (automated targeting)
-Non-ship units
--Starbase
---Construction
---Combat
--Weapons Platform
--Troop
---Infantry (planet defense)
---Armour (planet offense)
Non-Military
-Explorer (high speed, extra supplies)
-Transport
-Coloniser
-(Resource) Extractor
-Terra/Astraformer (for Stellar Manipulation)
Special
-Space Monsters
-Racial Specific
-Technology Specific

Having much larger ship classes available would fit the ethos of a game allowing Ringworlds and Dyson Spheres and also allow for the more "significant" items of Stellar Manipulation to be made much larger, requiring bigger ships (a planet buster should need to be Death Star sized at least...).

The downside is that forcing roles on specific classes could limit player flexibility in fleet design - but for multiplayer games it gives a reasonable idea of opponents' fleet makeup (e.g. offensive/defensive).