I spent several hours Thursday night re-reading Cassandra docs and doing another test install. I am trying to decide between MongoDB (which I have a fair amount of experience with) and Cassandra for a 2 node setup where I care less (at least right now) about latency than about redundancy and convenience. I want to (initially) use an EC2 instance and a non-Amazon VPS and since I can't tell from reading the docs (and I have not seen any published comparisons), I am going to have to set up both a 2 node Cassandra install and a MongoDB replica-pair to see which does better given the hit of one service running in an east coast Amazon availability center and the other in a data center in Texas. If I am ever fortunate to have more than a few users so performance becomes an issue, I would like to add another EC2 (or two) to the mix, but still keep a service running in a non-Amazon data center.

If anyone has any links to Cassandra/MongoDB comparisons for my desired setup I would appreciate seeing them.