Regardless of whether they're backed by SSD, all EBS volumes on an instance sit behind a 1 Gbps pipe (except for the more exotic and expensive instance types). That's part of the reason why Amazon talks about IOPs instead of raw disk bandwidth.

Go ahead and run:

  $ sudo du -hs /*

..on a vanilla m3.* instance and run iotop in a different session. You'll see bandwidth numbers that 2002 would be embarrassed about.

Bandwidth available for EBS volumes varies. For instance, with EBS-optimized volumes it can be 500Mbps, 1Gbps, 2Gbps, or 10Gbps, depending on the instance type, as shown in this chart from an Amazon presentation:

http://cl.ly/image/440b142t0T1x/Screen%20Shot%202014-12-18%2...

The "NA" of the 8xlarge instance types is because there's no ebs-optimization as an optional feature on that instance type; you automatically get access to 10Gbps.

Here's a video of the whole talk: https://www.youtube.com/watch?v=3OH4-Hx3tlE

Here's the slides: http://www.slideshare.net/AmazonWebServices/stg302-28617072

The SSD EBS claims a default performance of 3 IOPS/GB with a burst of up to 3000 IOPS with a 99% consistency. One of my larger instances uses SSD EBS and so far I am happy with it. In particular, I was very impressed how much faster updating Ubuntu was when I first booted the instance. I am planning to move my Postgres RDS instance to SSD EBS next week. I think (I hope) it will fix a particular stall my application experiences sometimes.