As far as I know Mieles test the viscosisty of the water and accordingly adjust the water and rinse parameters. I don't know if the Miele 3039i does the same but I think that will be an excellent washer based on the good old values of Miele and that the i is more towards Miele's Higher end of their range. Personally I think it is one of Miele's best machines.
It looks fantastic in a austere sort of way, rather conservative but timeless and elegant, and something that will still look good in a few years.
So I really hope that you will buy the machine and take some photos and videos thereof.
I am as excited as you!!
Regards,