When you say low latency is all important to you because you play your compositions "live", what do you mean? Don't you play/sequence one instrument (even polyphonic) in at a time? Are you saying that Logic and MacOS are inadequate for that? My M.O. involves importing the MIDI of a Sibelius score into Logic and working on it thereon. So my work on the DAW consists of EQing, automation, etc. and mixing, but not with frozen tracks. All tracks are "live" tracks right up to bouncing. In addition, not mentioning RAM at all in your post, makes me assume that it is not a main concern. I'd appreciate your - and everyone else's - insights.
I do play one instrument at a time, but nothing is printed until I get to the end. Obviously I could freeze instruments as I go, but then I'd have to un-freeze to edit and that would be a waste of time for me. I wouldn't be able to work this way using OSX on the computer that I have (which is sort of equivalent to a 2010 mac Pro).
However, the way that you work means that you can work at a much higher buffer so I don't think you'll have the same needs as I do.
Look, in the end the best you can do is to get the demo, when it's available, and try it for yourself.
DG