Platform x64 argument

Folks, one of my colleagues insists on compiling everything as platform x64 mainly because he thinks "it's an x64 world and it creates a better impression". For a year I've tried to convince him that for managed code that it's a complete waste of time. I've told him that ildasm.exe shows that for x64 and AnyCPU the generated IL and the manifests are identical, I even told him that dumpbin.exe shows the only non trivial difference in the PE headers is a couple of flags that show x86/x64 and PE32/PE32+, but they don't affect the loading and running of a PE containing IL and metadata. Does anyone have paradigm-shattering evidence I can give my colleague to break his habit? (I'm hoping I'm right of course!!) *Greg*