Although MacOS uses a 32-bit kernel by default with 64-bit applications in user-space, those who use a MacPro (which is 64-bit kernel by default with Snow Leopard since mid-2010) or another Mac computer with the option of booting into 64-bit enabled (like me) it would make a world of difference. MacOS booted into 64-bit kernel mode has shown to have a 30% performance increase in resource intensive applications like Aperture and Photoshop.
Working with samples and recorded audio also sucks RAM dry, so being a 64-bit app would also open MU:LABs doors to up-to 16TB of RAM to play with, rather than the 3GB 32-bit limits it too before using virtual memory space and bogging down.
Any Intel Mac can support 64-bit applications, weather the Mac's EFI supports a 64-bit kernel is a different story, but it still stands that any Intel Mac can use 64-bit natively.
Just my thoughts on it all
