Amazon RDS t2.small as a production server I currently have a m3.medium as production PostgreSQL server but I want to move it to RDS with the Multi-AZ feature.

Since the CPU usage of our current server is never higher than 5% and the RAM usage is 500MB I was considering using a cheaper instance like the t2.small on RDS.
On a few online forums and on Amazon help pages they don't recommend the small instances for a production database.
Is this just marketing or are there some real technical issues that may come up?

The only difference I found between the t2 and m3 instance types is the burstable CPU but since our DB server doesn't use any CPU I wonder what the other dangers are.
T2 instances are given cpu time based on a credit system, and t2.micros are have the least overall cpu capability in the instance class. These credits are accumulated at a rate of 6 per hour on a t2.micro, which gives you the ability to burst to 100% of the cpu core for 6 minutes. All other times you are only granted 10% of the core. Furthermore, you will only accumulate credits if your instance is completely idle.

http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/t2-instances.html

Depending on the purpose on your production server, and how much downtime is acceptable, ... you can always start with a t2.micro, and upgrade the instance if you see that there is need for more resources. Mostly you can upgrade the instance type in 3-5 minutes. Just power off, upgrade type and power on. I think that's more than a reasonable 'maintenance downtime'.