I'm planning to upgrade to 0.18 today and move the storage to S3, so I'll bring the instance down between 5-6pm PDT.
Update: this took longer than I expected. I started at 6pm because of work. I shut down the instance and took a snapshot, then brought it back up and upgraded to 0.18. The upgrade worked fine. I brought the services down and configured the instance to use S3 for object storage. That required migrating existing objects to an S3 bucket, which took quite some time. Then, after bringing the services back up again I got a "Server error" message. Unfortunately I had to stop at 8pm since I had something scheduled. At 9:15pm I was able to bring the services up successfully, and we're back!
Update 2: turns out we hit this bug, and the instance was down around 11pm. I changed the hostname of the instance and now it seems to be working fine.