Yep, you got it Horizon. Means to do anything much they need to put some guns into it.
LS, I don't mind scaling quality, but I would only implement 1 of your 2 suggestions, either/or. This is because with a 4+ save (say) on my grand cruiser (other races have 3 shields, 2 more hits and generally cost less) every second turn I'd have 1 shield. Half of the remaining turns (every 4th turn) I'd have 2 shields. Then 3, blah, blah.
Let's illustrate: 1st turn, enemy shoots 1 salvo at my 1 shield ship. Damage is taken, shield absorbs 1 hit, BM is place, brace saves made, crits for hull damage rolled, all as per normal. Now I get to do my 4+ regen; fails. Only had 1 shield this turn, subsequent fire resolved as normal.
2nd turn rocks around, same thing, but this time after the shooting resolves I regenerate (yay!). Now, if he fires again then I'll have gained a 2nd shield this time (possibly 3 if it regenerates and he fires again). However, he may not even shoot at that ship again (since the shield has regenerated he might fire elsewhere, or he may have fired all that he could or he may be depending on ordnance to finish the job, etc).
3rd turn, there's a lot of squads shooting at the ship and they manage to regen a lot so shields absorb 3 hits this time (same as a normal CG). Etc. So this would be considerably weaker than just giving the ship 3 shields.
When we're talking BB levels I don't think that 1 shield is enough. So, how about a flat 4+ save, allow multiple shields on larger craft, but only allow a shield to regen once per turn. So if it's successful it can't then regen again later.
Ugh, nevermind, ditch the whole idea and just give them normal shields.