Absolutely. Basically, as long as your app is running somewhere with Very Good Latency to your database, this can be a fine pattern. In practice, this means if the data center is also in Ashburn, Virginia, and better yet, has a DirectConnect deal set up with AWS, you should be in business. The best way to test this is to provision a database and see how latency from your app is. My opinion is that 5ms latency would be a ceiling on what I'd tolerate for my own apps, and I'd probably look for more like 1-2ms or better.