So I will say this is a nifty feature. A redis-style database for top ranks is great.
The problem though is that it stores the userid, so this unfortunately makes it difficult to make use of since I would otherwise require setting up another table that only contains connectUserID -> In-Game-Name to query each for to get public names for presentation.
I feel like it'd be great if we had the ability to put custom values in (override for userids) to make more efficient use of this.
Also, I assume some games access this via client-side. It should be obvious that this goes against privacy terms of service for sites like ArmorGames and Kongregate, providing methods people to access other member's user id's. I imagine this is a MAJOR a problem on Facebook terms as well.
It doesn't take much for someone to get access to this from the client-side for any game that uses the client to retrieve these values