My design preference is to make sure the default option feels natural in the f# or ironpython interactive console. I should be able to interact with Riak with no XML and one line to connect. Obviously it's only 2% but it's the first 2%.
Would you consider this to be out of the question:
open CorrugatedIron.Comms
let cluster = RiakCluster.CreateFromConfig("section", "path/to/file.config")
let client = cluster.CreateClient()