Let's just focus on Hyper-V on either 2008 R2 SP1, or Hyper-V on Server 2012. The guests are all modern versions of Windows themselves, either Windows 7 or 8, or 2008 R2 or Server 2012.
Do I really need to install the Hyper-V Integration Services on my guests? Everything seems to work just fine without them. And I understand why they may be necessary on older versions of Windows or of course non-Windows OSes...
I read a bit about what the Integration Services are for, but I could not find any information that was specific enough to convince me that I need to worry about installing them on Win7,Win8,2008R2,etc., guest OSes.