I have the same query
I have a similar query. I am using a MacBook Pro and will soon have a MacBook Air. Presently, I use a Time Capsule for the MBP. I also make Carbon Copy Clone copies once in a while of the MBP. I want the MBA to be available as a "plan B" if my MBP should fail for some reason.
I have several iOS devices (iPad and iPod, no phone) and these are all set up to sync with the MBP. I use only one Apple ID.
My real concern is the ability to sync music and photos and such with the MBA.
I read about home sharing setups and use of iCloud. For me, iCloud is not a practical option. Internet connection is way to slow and unreliable.
I'm just not clear on the aspect of duplicating files for iTunes on both machines