The rate limit is of course for the API, not the streaming API...
If you exceed the 600 requests in a 5 minute window you will get 429.
If you go higher and exceed the AWS limit,
we ban you manually
your IP address does not match the IPs in your API restricted_ips list you will get 403.
How long you back off depends on the limit, your number of requests and the 5 minute window of course.
I would be concerned if you are sending more than 2 per second. If you need bulk data, we have a number of products that may be of use to you.