Yeah its all gonna be about how many VIs and plugins you want to run.. I came from a 3.33Ghz hex-core 2010 Mac Pro w/24GB and my month old i7 Mini with 16GB is pretty much neck and neck performance wise. I think the CPU meter is a little bit lower with the Mini than the Pro but maybe 1-2% across the board (it falls around 20% for a 24 track session with Brainworx SSL G channel strip on every track and a crapload of Soundtoys and Eventide stuff..). I pretty much went back to all hardware over the last few years so I very rarely get into virtual instruments now except for the occasional Absynth or Alchemy track, so all I use Logic for nowadays is basically a tape deck and a mixing board. Since getting my MPC Live last year, I stopped writing in Logic altogether and went back to the old way..
The weird thing is.. Most of my projects hover between 20-25% CPU usage.. On the Mac Pro, it would still overload every now and then and stop playback. Wasn't a disk error either, it was the CPU crapping out, yet the meter never went above 25% and this was just simple playback?? No automation, wasn't messing with anything live, etc. The Mini just keeps on keeping on like there's no tomorrow. For years I dreaded the day I would have to leave my beloved tower design, man I dont even miss that thing one bit. Id bet my CPU meter would actually drop down a bit and waste the Mac Pro if it weren't for the UHD graphics. Ill have to see what happens when I finally get a GPU next month for my RX570..