I can't find anything in the documentation on if it is possible to change the current class of a bucket. Is this possible?
If this is not possible, what would be the most cost efficient way to move contents (10TB, hundreds of thousands of files) from a DRA bucket to a Nearline bucket? - Since I have all that data available locally, would it be most cost efficient to delete the old DRA bucket and re-upload everything to the Nearline bucket? (I'm not in a hurry)
We just announced the efficient solution noted in my Mar 12 answer: Please see https://groups.google.com/forum/#!topic/gs-announce/gZ4EvHoZns8
GCS will provide an efficient solution for migrating data to Nearline storage by the time the product is generally available. In the mean time you could create a new Nearline storage class bucket and copy the data to that bucket using the gsutil cp -D option (see https://cloud.google.com/storage/docs/gsutil/commands/cp#options). Note that doing this causes the bytes to flow through the machine where gsutil runs, which is slower that the mechanism we'll later provide and also will incur egress charges. You can mitigate the speed problems partially by running this gsutil cp -D command on a Google Compute Engine instance (since then the bytes won't need to flow over your ISP link).
