Deltons are a good rifle. They aren't top shelf, but in the ar world, there are very little differences that separate the "elite" rifles from the cheaper ones. The mechanics of all ar's is basically the same, and as you said you don't like your trigger. That's common with them, keep in mind they are designed to mil specs, so durability trumps the little things. The lowers of all ar's are all the same too. It's the finish that you tend to pay more for, but a flat black rattle can fixes any issues with finish. I would just see how she shoots. I've heard good and bad things about their barrels.
Remember to keep it lightly oiled as too much causes issues. Most guys use Mobil 1 5w30