Probably moving to 2010. I have been testing both 2009 and 2010. 2010 in more stable in the workspace and they corrected the plumbing/sloped piping. It's a big change due to the file format change, which traditionally, Autodesk does on ODD number years. We are using the 32 bit version, due to hardware constraints. 2011 is coming out in a month or less. You may want to see if that works for you since you are upgrading. Unfortunately, I have not seen what the changes to 2010 are in 2011. If anyone has a list, I would LOVE to see what the anticipated changes are.