All Windows devices, be it your RT, Pro, Win8 Desktops, Win8 Laptops, Win Phone 7.5/8 IF THEY SHARE the same Windows Live account they can be set to share settings across all devices mentioned above. Make a change to one Contact and it will auto populate to the others. Plus more settings can be shared across devices.
do you think that is a real benefit? I ask because I am simply in love with Google Now and a few other features. I understand I may not be able to change settings on my android device, but if my email/music can sync appropriately then I don't think its a HUGE problem.
I don't think the Windows ecosystem is tight enough at the moment to offer any significant advantage. In fact I hope it doesn't become that way because then you have Apple. MS has done a good job of being able to pull in info from other sources like Google and Facebook to a live account and that is fine with me. If your heart is guiding you to a nexus 4 I say go for it. I'm the happy owner of an HTC One X and wouldn't have it ant other way