According to what logic?  You can't mean linear progression, because that's a rather poor scale.  The armor/tank/dps of an Assault bot is more in line with the upgrade from Frig to Cruiser, not 'marginally' better like the Frigate > Destroyer, which is just a glorified Frigate with more gun slots.

A Sequer is 80U cargo, a Lithus is 240U, I don't think hauler tiers in EvE scale 4x?  Even with T2  expanders and rigs ...