http://www.youtube.com/watch?v=S7Bx_AqgMNw
I've played both back to back a few times and prefer the D-28.
If I was to get another D-18 I'd get a pre-2012 D-18.
I love the old straight bracing on D-18s. Yes the 2012 model is more like the vintage D-18s but the straight braced model sounds more like the classic D-18 tone you hear in the majority of 1960/70 singer songwriter albums. Amazing guitars (especially after a few years play).