Thanks to lord Havoc the Nexuiz/ xonotic community the DarkPlacesengine has seen an ever growing number of improvements. I for one always wrote these off as mere visual enhancements.
After a quick bit of research that assumption has been proven largely false. Here's a couple of utubes that make the point.This first one shows off some physics handling. I don't know if this work is available to the public but you get the impression that it might be soon if not already. To any xonotic playersout there please chime in if this is old news or common knowledge.
http://www.youtube.com/watch?v=dw84y-iHiQ4
The second one is an IDtech4 map I believe. A nice terrain map not unlike those found in Serious Sam.
http://www.youtube.com/watch?v=v7Usnj80PhU
This is just a hint at what DarkPlaces can do.