Hi Jules,
I can’t seem to find a way to use the Introjucer to automatically generate Mac projects that are either 64-bit only, or universal 64/32-bit …?
These days, the Mac App Store is 64-bit - so while clearly this is something I can patch easily enough in the project file after it has been exported by the Introjucer; clearly it could be a bit of a chore to have to keep doing that. 
This also applies to plug-ins, of course…
I haven’t yet had a chance to check this for Windows projects… where the same basic problem might apply, I guess!
Best wishes,
Pete