The Smotherman totally fails to take into account the reduced effectiveness of low LB capacity though. 2x2 AC is roughly 2/3 as effective as 4AC, which gets the Defiant a 9pt points break.
So what do we want from the Voss? We want a Light Cruiser of the line. A ship that stays with the cruisers (so 20cm speed), can get into the line of battle (so 6+ prow), support the cruisers on their way in (modest forward torps), fight it out when it gets there (broadside firepower), and, unlike the larger cruisers, react to changing battlefield conditions (90' turns).
The Defiant additionally needs torps to make it worth reloading, and trading the Lances for FP4 WBs (A downgrade from 2 lances)