>>>I think they just changed the name

Steve just for the record Draftsight is not DWGeditor.
Draftsight is a rename of ARES a product that Dassault Systemes have OEM’ed from http://www.graebert.com

Now all those apps often called DWG clones which some if not all are basted on ODA's DWGDirect http://www.opendwg.org/

What ODA's DWGDirect does? Well what they really do is Reverse engineering of Autodesk's RealDWG. The reality is Autodesk's RealDWG is constantly changing so ODA's DWGDirect is always a step or two behind.

HOW to test a product like Draftsight. Go here http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=12456726&linkID=9240618 Download some of the test files, that will give you a good idea of what is supported ;)