We do a huge place on a very busy road near an even busier round about. The owners had spent a bomb having every window, etc, replaced with Pilkington glass on the basis of what the salesman told them.
The owner is currently taking Pilkington to court ref the Trade Descriptions Act and Sale of Goods Act.
When we did the windows for the first time earlier this year, they were so filthy that we used a jet wash for the first clean. Around the side of the house, which faces East and gets virtually no rain, the windows were thick with black grime.
We also do quite a few other places and as per the above postings, I don't think there is much to worry about from self cleaning glass.