For me the soul of D&D is not so much the mechanics, but the fantasy escape. I probably spent more hours reading through the AD&D books than actually playing the game, and generally I kept the combat mechanics pretty simple when I did play. As a DM, I rolled the monster hit & damage dice behind my screen, so that I could nudge the numbers a bit to make sure the players were having fun. A high level 8HD monster would have maybe 40 hit points, so turn-based combat was not too cumbersome.
I never played DOS, so when I do finally pick up this game it will be all new for me. And that is OK as long as the play is fun and the sense of immersion takes me into another world. I guess one aspect of D&D that I would look for is to be able to play a part in some of the nostalgic original stories revolving around places, names, and items such as the City of Brass, the Wind Dukes of Aaqa, or the Recorder of Ye Cind. Those are the things I often read about but have never gotten a chance to play.