I'd love to have a quick conversation about Target 20, AC, Saves, and the game!
If I'm reading Target 20 correctly, then there is still DM-facing information during combat for our rolls. Level+Stat Mod+AC, and you're trying to beat 20. Will you be telling us the AC during combat? Or are we only rolling the first two (level and stat bonus) and leaving the rest up to you? The first is much quicker in PbP, and I've never felt it removed the mystery. The second is more traditional, but slower and more likely to lead to confusion.
How are we calculating saves with T20? Is it Level + Save and trying to beat 20?