Compiling for IL2CCP - Net 2.0 Subset makes any difference?

When building for iOS devices using IL2CCP, does it make any difference if I select Net 2.0 Subset for my API compatibility level? I ask because I read that Net 2.0 Subset does not support System.xml but I think that I am using System.xml (XmlTextReader) and it compiles and runs just fine on my iOS 32 & 64 bit devices. *Am I* using System.xml? Thanks, Manny