The question is if can I use safely Visual Studio 2012 to edit projects properties, add and remove solutions, references, all related to NET 4.0 Framework.
I remember in the past some files might be "corrupted", while Visual Studio 2010 changed some Visual Studio 2008 csproj information (xml file).
If some tags are added/removed in VS2012, then the csproj would be incompatible to VS2010 developers.
Does anyone have some information if it is safe to use this new IDE without damaging files? Are VS2012 csprojs "backward compatible" with VS2010?
VS2012 projects are mostly* backwards compatible with VS2010 SP1. The projects will undergo a conversion/migration process like in all previous VS versions, but this one is friendly towards VS2010. You should be able to make changes to your projects/references/code files and open them again in VS2010 without issues.
I say mostly because there are some features new in VS2012 that may not be backwards compatible. The most obvious, if you upgrade a project to .NET 4.5, it will no longer work in VS2010. See http://blogs.msdn.com/b/visualstudio/archive/2012/03/28/round-tripping-with-visual-studio-11.aspx for more information about this scenario.
来源：https://stackoverflow.com/questions/10902865/is-visual-studio-2012-csproj-backward-compatible-with-2010