What is the point of using a dedicated Key-Value Store over Bigtable? My understanding of Bigtable is that it is implemented under the hood with SSTables which are key value based. Given that, then what technical implementation advantages does a dedicated Key-Value Store gain over Bigtable by throwing away the api that Bigtable exposes and keeping to just the minimal put and get api.
(*) I'm not sure which key-value storage you have in mind, allow me to guess.
A feature comparison can be found here: http://vschart.com/compare/dynamo-db/vs/bigtable
As you scroll down, you will see the proverbial devil in details, e.g. integrity model is different.