Cuda SDK 4.2 and 5.0 Interaction

We have a large project using Cuda 4.2 and Visual Studio 2010. We downloaded and installed 5.0 along side 4.2. We noticed the name change of the SDK utility functions (and include path macro). Rather than switch all the include files we just used 4.2 for these headers. Is there a functional difference in the types, and functions between the two versions? Will we have problems using both 4.2 and 5.0 SDK utility functions?