Nice Martin, Curly. My friend has a well used 71 D-28 and he doesn't even own a case for it! He just leans it against furniture and throws it in his backseat! Every time I see him, I ask him when he's gonna buy a $50 case to save his vintage Martin.
I like my D-28. Martins sure do play like crap when new, so it took me awhile to get it playing perfect. I scored my 2001 D-28 from a guy who thought it played terribly, so he sold it to me for $995. As soon as I saw that ad pop up in the recycler, I sped to his house to scoop it up. After getting the nut and saddle cut right, it plays perfect, and sounds like you'd expect the most recorded acoustic in history to sound.
The best midline Martin is a DR (Dreadnaught Rosewood). It's just like the DM, only the back and sides are high quality laminated rosewood.
Before I had the D-28, I had the DR, and I still think it's just as good as the D-28, only way cheaper. For around $650 used, the best acoustics IMO are the Martin DR and the Taylor 310 or 410.