It also eliminates a lot of weird contact list issues where you lose followers, etc

Really interesting how is blurs the lines between client and relay in a unique and useful way. There's real value in a client that's also a reliable, indexed *backup* of everything you care about. Not just performance, but ownership. This reminds me of Obsidian which I'm a big fan of.

And there will be an efficient way to sync between these nodes as well which is neat. This would replace notmuch-email for me

Did you use strfry for the storage layer?

The design of nostrdb is identical to strfry, its built on lmdb and uses the same index structure. it may be even a bit faster because ive made further optimizations during json processing.