This is my opinion. The reason why the 5er front fascia works the best and the G11 7er to a lesser degree is that the headlights present a more full headlight enclosure vs. the F30 which has a more slim look, leading to a thin and flat front. If the G20 follows the 5er more than the F30, it's going to be a hit. If not, prepare for more moans and groans. To be honest, the headlight is probably the worst feature on the F30 for me. I didn't like it when the F30 was revealed, still don't like it today.
What Mercedes doing what they have with the C-Class, the F30 looks even more pedestrian than ever.