I call it "close combat" because i can hardly call it "hand-to-hand" or "melee" combat. Anyway - I am somewhat in the middle of the game and have 31 DT (from armor, implant and perks) and still small critters almost kill me when the succeed to get close. And as "small" critters I don't mean deathclaws. I have about 250 HP and it seems I get almost killed with just 2-3 hits from the critters. So if the DT is not negated those hit should make 100+ damage per hit... kinda reminds me of the almighty boars from Gothic 3.

I'm pretty sure DT is taken into account. I came up on some creatures (night stalkers I think), and I had toggled my armor off to move faster and forgot to toggle it back on. I got decimates. I reloaded and tried again, this time with armor, and it wasn't nearly as bad. Obviously it isn't a 1 to 1 comparison because i'm sure they and I did different things, but it certainly felt like it made a difference.