Like many others, I found this by searching for a replacement for Lazarus (RIP). While it doesn't yet measure up to Lazarus, from what I can tell it's one of the only alternatives available. I can't for the life of me understand why there aren't more options for form saving since every single one of us has wished for it at one time or another.
I don't yet know whether Textarea Cache will save me when I need saving. I won't know that until I've accidentally closed the browser or lost a form, and need to recover my text. But it seems like a good start, and I'm happy there is at least one dev working on this.
Wildsky: you seem to be updating this often, and responding to comments/reviews as well, so I can only hope that you stick with this project and that it continues to improve. Cheers!