DWG files in 2010 format should work the same as 2004 DWG format when it comes to WAN accelerators. The ACADCOMPRESSIONMODE envirionment variable is not needed unless you work with DWG files in 2007 format. This according to this Autodesk forum discussion thread.
Previous posts on the subject:
WAN acceleration hotfix for AutoCAD products and DWG files
Riverbed and DWG 2007 file format workaround