I mostly want an alternative to shields, other than simply having thick enough armour to be able to make it home, but then you have to pay for the defense in blocks every battle whereas shields is just energy. Granted, if you shield tanked in EVE and didn't bother to swap on armour/hull repairers then you still had to pay for your repairs in that game too.
I'm a tank/support/healer player RP wise, so I approve of finding an alternate method of defense that doesn't feel like I'd be throwing blocks away.
The only way to do that would be to abstract an 'armour health' value, which just means its the same mechanic as shields but with no sustained cost if your armour HP is full. The only meaningful difference this would make in defense is having alternate tank styles in your fleet so that your opponents couldn't equip only anti-shield guns and win, or only armour/block piercing ones. However, I don't like the idea of abstracting armour health value, then it takes away from the hull design of physically protecting your systems with several meters of plating.
I currently see little use for the Astrotech module, perhaps make it affect all blocks on the target ship but at a lower rate? that sounds like a massive lag headache thou. I'm tired and should go to bed, as I don't think I've actually added anything to this discussion, hopefully some of my rambling provides ideas for others.