I'm new to mini but just came from the world of audi tuning. The N18 motor is very similar to the 2.0 tfsi and fsi setup. I think it's a german standard now. The Audi's have been notorious for burning a qt of oil a month. .lol. The reason... PVC design. All gasses and sludge are routed to two places, the intake and valve cover.
Audi designed this for environmental reasons and epa standards. The big trend right now for Audi and VW tuning is catch cans. Audi has had tons of problems with valve deposit build ups. To the point that there is service bulletins like crazy.
I ran a catch can on my 2008 A3 and I was shocked how much junk was being sent to the intake. Then when I upgraded my intercooler I was more shocked to see oil pour out the intercooler piping.
I would not recommend blocking any pvc ports on the valve cover at all. Just reroute the flow into a catch can.