> *Although a change in the error code would not affect our application, is
> there a place where I can read more about rate limiting and its criteria?*
I'd second knowing a bit more about the rate limiting. What is
it targeting? IP, Consumer Key, User Access Key?
In my case, 98% of my use of the API is with centralized data servers, not
via distributed consumer applications, so how Tumblr rate limits requests
is of interest / concern to me.
I don't believe I've run into the 503 "rate limit" response in the past,
but my code tends to treat any 500-type errors in the same way without
differentiation, so it's hard to say with certainty.