Would you recommend it for production use?
Is there a suite of compatibility/performance tests that is run on AWS for each release?
The releases are completely stable. I'd go so far as to say that FreeBSD/EC2 is probably more stable than FreeBSD on native hardware, simply because you're less likely to run into weird driver issues with obscure hardware.
Would you recommend it for production use?
Absolutely. I've been using it for Tarsnap for years.
Is there a suite of compatibility/performance tests that is run on AWS for each release?
Not that I know of.
The nicest experience I've had is with the Ubuntu community AMIs. Ubuntu keeps a listing of their official AMIs[1] and there is a JSON api that they provide so you can fetch that information programtically.
It would be simple enough to extract the AMI numbers from FreeBSD release announcements though; the main reason I encourage people to use the Marketplace AMIs is that the AWS Marketplace provides useful statistics about how many instances are running.
EDIT: Hijacking my own comment slightly, since it's at the top right now: I'm not sure why 10.3-RELEASE being in the AWS Marketplace is a story when 10.2-RELEASE, 10.1-RELEASE, 10.0-RELEASE, 9.3-RELEASE, 9.2-RELEASE, 9.1-RELEASE, and 9.0-RELEASE being in the AWS Marketplace weren't. The hand-off from me to the release engineering team has been gradual (made slower by the fact that we only get to try something new once every 6 months!) but as far as users are concerned FreeBSD has been in the AWS Marketplace for years.