What in your opinion do the SCs need the 2nd shield for? To become what?
To let the Space Marines with Strike Cruisers be a fun and competive fleet. Easy enough.
More or less I'd like to see these 3 variants foremost:
Strike Cruiser - variant ICruiser/6, Speed 25cm, Turns 90*, Shields 2, Armour 6+, Turrets 2
Port WB, 30cm, 4, Left
Starboard WB, 30cm, 4, Right
Prow Launch bay, 1 Thunder Hawk
Dorsal Bombardment Cannons, 30cm, 3, L/F/R
Strike Cruiser - variant IICruiser/6, Speed 25cm, Turns 90*, Shields 2, Armour 6+, Turrets 2
Port WB, 30cm, 4, Left
Starboard WB, 30cm, 4, Right
Dorsal Bombardment Cannons, 30cm, 5, L/F/R
Strike Cruiser - variant IIICruiser/6, Speed 25cm, Turns 90*, Shields 2, Armour 6+, Turrets 2
Port WB, 30cm, 4, Left
Starboard WB, 30cm, 4, Right
Prow Launch bay, 3 Thunder Hawk
Sumtin like that
edit:
then, again,
http://www.tacticalwargames.net/sg/forum/index.php?topic=1758.071 pages of Marine fun.