If disk performance is important you can also take a look at the High IO instances, which give you 2x 1TB SSDs, 60GB of RAM and 35 ECUs across 16 virtual cores.

If disk performance is important you can also take a look at the High IO instances, which give you 2x 1TB SSDs, 60GB of RAM and 35 ECUs across 16 virtual cores. At 24x7 for 3 years you end up with ~$656/mo per instance, plus whatever you would need for bandwidth. By the time you fill up an entire rack it still ends up being slightly more expensive than your amortized 2U cost, but you also don't need to scale it up in 2U increments.