I know its not supported but what issues might I encounter if I use version 2006.3 within Visual Studio 2008 and target the 2.0 framework?

I have successfully upgraded a couple of sites from VS 2005 to VS 2008, compiled as .Net framework 2.0 and have been able to run them. From what I can tell they run ok.

Are the issues with VS 2008 and older versions of Infragistics just a matter of problems when adding controls to a page while in design view? Does it also include adding a control while in source view? Or are the issues more serious than that?