I'm currently using HREs 19" now, they are definitely lighter than the OEM Carrera S wheels. I do not have any problems with the water issue, I live in a tropical city and rain is common.
As for the strength, I would not be able to ascertain but I will be bringing the car to the track soon. However, I'm sure it will hold out well against the OEM. My 2 cents.
I get many good reviews on the looks, many fellow enthusiasts would ogre and give more than positive compliments.
Hope the feedback helps.