Luke Johnson over at "What Revit Wants" recently posted a blog on round tripping Revit to Impressions to AutoCAD and back into Revit.
I believe Impressions is a little known and under utilized program that is available to many Subscrition members. It's a great program to use and in some instances can replace photoshop completely... it also recognises when changes have been made to a AutoCAD file and can update your Impressions file.
It's another tool for your utility belt !!
Check out Luke's blog on Revit - Impressions - Photoshop - Revit here.
And check out the Impressions web site here. Impressions Community