As I was reading about the problems this system needs to solve and the issues with Kyoto Tycoon, I thought that LMDB might be a good foundation for a solution. So I was gratified to find out that Quicksilver indeed uses LMDB. I gather Cloudflare has found that LMDB is indeed as reliable as it's advertised to be.

Looking forward to the eventual open-source release of Quicksilver.