Right now we're still seeing way more requests to the boundary detail endpoints than we're going to be able to handle, and unfortunately without API keys and from different IP addresses so it's been more trouble than it's worth to block/throttle them all.
This is one of the reasons we accelerated our plans to require API keys, I'm hopefully we'll at least have a better handle on where this traffic is coming from.
Also, somewhat relatedly, as we look at usage of this particular endpoint, we're giving serious thought to deprecating it altogether. This is static data that almost never changes, but is quite large. There are better ways to handle this. Some people are requesting the same boundary hundreds of times a day, which isn't what this endpoint was originally intended for.
Right now my gut feeling is that these endpoints are probably best replaced by offering bulk data going forward.