Just to follow up: Had the D5s for a bit now, and my main lessons are as follows
1. A little break in goes a long way! When I first hooked them up they sounded so bad I thought I had somehow miswired them or something. Extreme brittleness, serious and immediate ear fatigue and general crappiness. I intermittently played pink noise and internet radio and medium-loud volume for several days in a row. HUGE difference. Now they sound much more balanced and "round".
2. They are very unforgiving (in a good way). If it sounds bad, you will know it immediatly. There is no leeway, no glossing over trouble spots. They seem very, very accurate in the midrange and as a result a lot of warts are showing up in mixes I originally thought were "OK".
3. They do not have much in the way of low end. This is taking me a while to get used to, but playing commercial CDs a bunch and listening to what they offer is beginning to help. I may end up with a small sub to hear the umphh I am missing. Despite the lack of low end, I really like the overall balance. I just need more time to really get accumstomed to their sound.
That's all! For $300 I cannot imagine a better set of monitors. Huge improvement over the Alesis MKIIs that I had (I realize that is not saying much). Anyway, hope someone finds this helpful.