The SoK is not too powerful, doing the viking to get more greater rhinestone is utterly pointless, if repeating Settlements it would be much better to do Japanese as dojo also provides a unit and is almost as efficient at FP production and completing the settlement is so much easier. It will also be expensive to upgrade all SoK and that keeps it balanced because we won't able to fill our cities with them overnight. Given how underpowered SoK had become, making them very slightly overpowered isn't really a problem. The trend of last years event buildings being so good is only like to continue and if this change hadn't been made SoK would have fallen even further behind.
Doesn't make much difference to me anyway as I only have a handful, because I don't like having too many buildings that need motivating. Yes it makes Terrace Farms even less desirable, but the solution to that is to get rid if the Terrace Farms as soon as you can, that's what I'm doing and it is no great loss, they are still useful buildings.
Awesome development.