Okay, Orks. Kroozers only have one void shield, so unless you are running the No Salvo rules the extra armor does not make up for the lack of a second void shield.
Against a Kroozer with 23 armour: Dual Sunsears with and without salvoing (S-RAW & S-NS), a mars cannon with a Titanforge lance (L-RAW), with tearing (L-T) or allowing multiple hits (L-MH)
K S-RAW S-NS L-RAW L-T L-MH
30 0.35 0.09 0.86 1.00 0.86
40 1.73 0.83 1.52 1.79 2.47
50 3.63 1.68 2.38 2.79 4.28
60 6.06 2.65 3.42 4.02 6.27
70 8.96 3.72 4.66 5.47 9.41
Compare with a Cruiser with two void shields and 20 armour. I didn't have Lance with Tearing vs Cruiser available.
C S-RAW S-NS L-RAW L-T L-MH
30 0.18 0.11 0.57 0.57
40 1.07 0.71 1.14 1.52
50 2.46 1.51 1.90 2.85
60 4.34 2.50 2.85 4.56
70 6.71 3.70 3.99 7.60
).