Now that is a reasonable concern. Keeping db hardware happy is certainly an expensive undertaking. I think I'm more used to the arguments like the one from Sauce Labs, where the VP whines, "What are schemas even for? They just make things hard to change for no reason. Sometimes you do need to enforce constraints on your data, but schemas go way too far," [1] and then goes on to say that his company is moving from using CouchDB to using MySQL as a key-value store with serialized JSON (data integrity and performance be damned -- I mean, really, the thought of converting millions of values in a table to objects just to run a home-grown MapReduce function on them when you could just LEARN HOW TO USE MySQL is pretty much the most insane thing I've ever heard lol).

Do you have any experience with Amazon RDS? I haven't tried it; I guess my concern would be the same as any other AWS product--they tend to fail catastrophically from time to time. Then again, if you're doing cloud NoSQL through Amazon, you're going to run into the same issues (see: Reddit).

[1](http://sauceio.com/index.php/2012/05/goodbye-couchdb/)