Hey it's me again... Check out this image.... Does your Prefrences for Audio have a menu like this?
If it does then notice the "process buffer range" option. If you try setting that to low for example, or play with the settings, see if your POPS/CLICKS become less apparent or more frequent with the HIGH setting.
Another thing that will definitely affect the POPS/CLICKS is your Frequency Setting.... I wonder if you have it set to 44Hrtz or 48Hrtz? Because if you set your Reason settings to 48Hrtz it will DEFINITELY effect or HELP with your issue! (It will only work with a powerful computer, which you have in this instance). I saw your image of your reason prefs, it shows that your setting is 44Hrtz. Change that and you will compensate lost latency for the above "process buffer range" setting! It means that when you have PBR set to LOW, a setting of 48Hrtz will lower your MIDI note latency. It's really complicated, but if you pay attention, you will understand.
I just know the exact issue this is, but since I can't see the MAC settings LIVE I can't be sure what your particular setting look like.
This should help you zero in on your issue.
Let me know how it goes.