The vsd puts put more firepower per point spent than the ISD
You need to upgrade the ISD for offensive output, not the VSD
Could you elaborate on that please? If you calculate bow firepower the VSD II pays 14,1pts per die, the ISD II pays 12. Calculating all-around firepower (14 dice on a VSD, 21 dice on an ISD) its 6 pts per die on the VSD against 5,7 pts per die on the ISD. Braking it down on ranges is not going to cut it as the relation of long/medium firepower on both ships is equal/bow or very similar (all around). Not mentioning that your ISD platform carrying that firepower is actually more durable and more agile.
VSD II = 83 pts, 6 front dice = 13 pts/dice
ISD II = 120 pts, 8 front dice = 15 pts/dice
Woops, had 5red/5blue in mind somehow, and only a short look at fabs. My bad. Still, rounding down 13,83 to 13 is not good sport either. All around its still 6 pts on a VSD compaired to 6,3 pts on an ISD, on the bow I pay 1 pt more per die, still on a far more durable and maneouverable platform. So for raw firepower its still ISD most of the time for me..