Well, doing movie-style "insta-gib" is harder if you're also doing realistic armaments. But the canon is so contradictory with technical things that you have to use some kind of standard, and I chose X-wing series units, so it probably plays more like tactical XW than anything. So that means a single concussion missile will take out most fighters and hulls can generally take a couple of laser hits before totally breaking apart. But turbolasers will almost always miss fighters and lasers can't target capitals very well.
I don't find the movies to be necessarily representative of things like shield and hull ratings... I think you can write a lot of that stuff off as critical hits or, at the very least, storytelling. And who's to say shields were ever at 100% when you see these ships being destroyed? It's just too much over-analytical fanboy speculation as far as I'm concerned, so I opted for balance in that respect.