1.) Penetrating - 2 vs. Halves Shields...
Is it just me, or is Pen 2 strictly better than Halves Shields, and at the same cost? It will have the same effect against shields 4 or 5, and be less effective against shields 3 or less...
All of the point values are worked out on an average basis. For example, the ratio of impact rolls to successful hits is:
No shields = 1:1
Shields 1 = 6:5
Shields 2 = 3:2
Shields 3 = 2:1
Shields 4 = 3:1
Shields 6 = 6:1
The average ratio is 2.45:1.
With Halves Shields, this becomes:
No shields = 1:1
Shields 1 = 6:5
Shields 2 = 6:5
Shields 3 = 3:2
Shields 4 = 3:2
Shields 5 = 2:1
The average ratio is 1.4:1, or 1.75 times more effective.
With Piercing +2, the ratios are:
No shields = 1:1
Shields 1 = 6:5
Shields 2 = 6:5
Shields 3 = 6:5
Shields 4 = 3:2
Shields 5 = 2:1
The average is 1.35:1, or 1.81 times more effective.
So, you are correct -- Piercing +2 is "better" than Halves Shields, but only by about 4%; and they only differ against targets with Shields 3.
2.) Theres nothing wrong with our bloody ships today...
It seems to me that the presence of major penetrating advantages on most ships big guns will serve to 'wash out' most of the advantage that BBs have over BCs in terms of resilience. While the BBs are still tougher, they are not very much tougher against the big 15" guns, making BC's a likely better point-for-point investment.
Remember, this is just a quick-n-dirty "what if" for Starmada on the high seas. If you want something more in-depth and realistic, look for the second edition of Grand Fleets.