Interesting. Now that ARC is in the picture, I’d think this would be overkill/confusing.
I’d move the core to the mini. I’ve been lifetime for a few years now, and I am pretty sure I did my trial on my MBP, and then just moved it to the mini (also a 2012) when I knew I was going to keep it.
Mini stays put as a headless computer away from the stereo, and all my music files live there. I use the MBP (as well as my iPhone/iPad) as a remote.
You’ll use your phone as a remote (endpoint) when you’re using ARC at your second location.
Look at this thread for ideas for best sound quality with ARC at remote locations