Are there any actual(breaking) changes between 2008 and 2010 project files?

A while back I accidentally converted a project file to Visual Studio 2010(of course, no source control). Instead of recreating the project file though(which would have only taken about 10 or 15 minuteS), I instead looked at what changed between a typical 2008 project file and my converted 2010 project file.

The only difference I noticed was that in 2008, this is the second line:

<Project DefaultTargets="Build" ToolsVersion="3.5" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

And in 2010, it was this:

<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

To backwards convert, I just changed it to 3.5, and never had a problem with it(and soon checked it into source control!).

Now my question is this: Is there ever a case where you can't just simply change the ToolsVersion to backwards-convert? (Of cour开发者_运维问答se, assuming you're not using .Net 4.0)

As far as I know, it's just the ToolsVersion. However, VS2010 may put extra stuff in the project file that VS2008 won't understand. It may also add targets that VS2008 doesn't have.