I'd like an answer to the same question. I have a fully-loaded 2013 11" - i7, 8GB RAM, 512GB SSD - and I use it for work. It's also my desktop machine at times, docked to a TBD.
I wouldn't be opposed to upgrading to the newest 11" if there's a significant performance difference between the two models. Does half a GHz make for any real-world speed increase?
If there's anyone who's pulled the trigger and can give us some insight, please do!