Bucket Regions and AWS Signature Version 4
S3 Media Maestro now has AWS Signature Version 4 which supports bucket regions that don't have backwards compatibility for AWS Signature version 2.
Beginning in S3 Media Maestro 3.0.0, S3 buckets can be created and queried from within the plugin. This means that it's not necessary to manually set bucket regions in shortcodes. One thing to note is that there is backwards compatibility for shortcodes that have specified bucket regions within the shortcode for S3 Media Maestro version 2.0.4 and below.
Here is a list of current available regions and signature versions according to the AWS documentation.