Why UE4 over Unity? I have downloaded both and while both have a steep learning curve the one for UE is steeper, and the initial experience is much worse. Seems they never really tested it on the mac much.
I develop on the mac and pc in UE4. On the mac ue4 performance is bad and you need the top of the line mac to deal with it. Personally I just write c++ on the mac and keep the editor closed most of the time until i need to test the code real quick in a very basic level. Then when im on my pc i do the heavy stuff.