JST:
Honestly, from the point of view of subaru's and 40/60 rear-biased awd systems, the haldex Golf R system is likely weak sauce. It certainly will be after my s4 torsen+sports rear diff which kicked out like a RWD car.
Give the GTI SE spec a try, you might be surprised. I hadn't seen the chart below until after my drive. FXD is the front diff on 2017 GTI's sport package and above. It's also on 2015 or 2016's as the performance package, but hard to find.