Go for the 8X. You'll missed out on some Nokia extras (Glance, Nokia Camera, etc...) but the 1GB of RAM, better camera & screen resolution are worth it over the L720.
The only MS product I use is my L920 (I also have a HTC 8X as a back up). I've held of upgrading my iPad Mini to the Retina version because I want a similar size Windows 8 tablet instead, currently nothing available but I will wait for that Nokia 8 inch that there are rumours about. My Mac...